diff --git a/.gitignore b/.gitignore
index e483dff..73b0073 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+
 # rcov generated
 coverage
 coverage.data
@@ -15,7 +16,7 @@ doc
 # jeweler generated
 pkg
 
-# Have editor/IDE/OS specific files you need to ignore? Consider using a global gitignore: 
+# Have editor/IDE/OS specific files you need to ignore? Consider using a global gitignore:
 #
 # * Create a file at ~/.gitignore
 # * Include files you want ignored
diff --git a/README.md b/README.md
index ad2c698..f0a5147 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@ gem install blockscore
 If you are using Rails, add the following to your `Gemfile`:
 
 ```ruby
-gem 'blockscore', '~> 4.1.2'
+gem 'blockscore', '~> 4.2.0'
 ```
 
 ## Getting Started
@@ -60,5 +60,5 @@ To see the list of calls you can make, please visit our [full Ruby API reference
 The test suite uses a public BlockScore API key that was created specifically to ease the testing and contribution processes. **Please do not enter personal details for tests.** In order to run the test suite:
 
 ```shell
-$ rake test
+$ rspec spec
 ```
diff --git a/blockscore.gemspec b/blockscore.gemspec
index 7425d4c..0754300 100644
--- a/blockscore.gemspec
+++ b/blockscore.gemspec
@@ -29,6 +29,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'bundler', '~> 1.0'
   spec.add_development_dependency 'simplecov', '~> 0'
   spec.add_development_dependency 'rspec', '~> 3'
+  spec.add_development_dependency 'rspec-its', '~> 1'
   spec.add_development_dependency 'webmock', '~> 1.21'
   spec.add_development_dependency 'faker', '~> 1.4'
   spec.add_development_dependency 'factory_girl', '~> 4.5'
diff --git a/lib/blockscore.rb b/lib/blockscore.rb
index b652aa5..71e547a 100644
--- a/lib/blockscore.rb
+++ b/lib/blockscore.rb
@@ -1,3 +1,4 @@
+require 'delegate'
 require 'forwardable'
 require 'httparty'
 require 'json'
@@ -26,6 +27,7 @@
 require 'blockscore/watchlist_hit'
 
 require 'blockscore/collection'
+require 'blockscore/collection/member'
 require 'blockscore/connection'
 require 'blockscore/dispatch'
 require 'blockscore/fingerprint'
@@ -34,11 +36,7 @@
 require 'blockscore/version'
 
 module BlockScore
-  def self.api_key=(api_key)
-    @api_key = api_key
-  end
-
-  def self.api_key
-    @api_key
+  class << self
+    attr_accessor :api_key
   end
 end
diff --git a/lib/blockscore/actions/retrieve.rb b/lib/blockscore/actions/retrieve.rb
index e0585af..87725d7 100644
--- a/lib/blockscore/actions/retrieve.rb
+++ b/lib/blockscore/actions/retrieve.rb
@@ -11,8 +11,10 @@ module Actions
     # => #<BlockScore::Person:0x007fe39c424410>
     module Retrieve
       module ClassMethods
-        def retrieve(id)
-          get("#{endpoint}/#{id}", {})
+        def retrieve(id, options = {})
+          fail ArgumentError if id.empty?
+          req = ->() { get("#{endpoint}/#{id}", options) }
+          new(id: id, &req)
         end
       end
 
diff --git a/lib/blockscore/actions/update.rb b/lib/blockscore/actions/update.rb
index df9e25e..1de39ed 100644
--- a/lib/blockscore/actions/update.rb
+++ b/lib/blockscore/actions/update.rb
@@ -28,7 +28,7 @@ module Update
       def_delegators 'self.class', :endpoint, :patch
 
       def save!
-        if respond_to? :id
+        if persisted?
           patch("#{endpoint}/#{id}", filter_params)
           true
         else
diff --git a/lib/blockscore/base.rb b/lib/blockscore/base.rb
index b19d657..b56d3b4 100644
--- a/lib/blockscore/base.rb
+++ b/lib/blockscore/base.rb
@@ -4,19 +4,37 @@ module BlockScore
   class Base
     extend Connection
 
-    attr_reader :attributes
-
-    def initialize(options = {})
+    def initialize(options = {}, &block)
+      @loaded = !(block)
+      @proc = block
       @attributes = options
     end
 
+    def attributes
+      return @attributes if @loaded
+      force!
+      @attributes
+    end
+
+    def force!
+      res = @proc.call
+      @attributes = res.attributes.merge(@attributes)
+      @loaded = true
+      self
+    end
+
+    def id
+      @attributes.fetch(:id, nil)
+    end
+
     def inspect
-      "#<#{self.class}:0x#{object_id.to_s(16)} JSON: " + JSON.pretty_generate(attributes)
+      str_attr = "JSON:#{JSON.pretty_generate(attributes)}"
+      "#<#{self.class}:0x#{object_id.to_s(16)} #{str_attr}>"
     end
 
     def refresh
-      r = self.class.retrieve(id)
-      @attributes = r.attributes
+      res = self.class.retrieve(id)
+      @attributes = res.attributes
 
       true
     rescue Error
@@ -45,16 +63,18 @@ def self.api_url
     end
 
     def self.endpoint
-      if self == Base
-        fail NotImplementedError, 'Base is an abstract class, not an API resource'
-      end
+      fail NotImplementedError, 'Base is an abstract class, not an API resource' if equal?(Base)
 
       "#{api_url}#{Util.to_plural(resource)}"
     end
 
+    def persisted?
+      !id.nil?
+    end
+
     protected
 
-    def add_accessor(symbol, *args)
+    def add_accessor(symbol, *_args)
       singleton_class.instance_eval do
         define_method(symbol) do
           wrap_attribute(attributes[symbol])
diff --git a/lib/blockscore/collection.rb b/lib/blockscore/collection.rb
index e81284d..b1b4f12 100644
--- a/lib/blockscore/collection.rb
+++ b/lib/blockscore/collection.rb
@@ -1,18 +1,239 @@
 module BlockScore
+  # Collection is a proxy between the parent and the asssociated members
+  # where parent is some instance of a resource
+  #
   class Collection < Array
-    def initialize(target)
-      super()
-      @target = target
+    # @!attribute [r] parent
+    # resource which owns a collection of other resources
+    #
+    # @example
+    #   person.question_sets.parent # => person
+    #
+    # @return [BlockScore::Base] a resource
+    #
+    # @api private
+    attr_reader :parent
+
+    # Sets parent and member_class then registers embedded ids
+    #
+    # @param [BlockScore::Base] parent
+    # @param [Class] class of collection members
+    #
+    # @return [undefined]
+    #
+    # @api private
+    def initialize(parent, member_class)
+      @parent       = parent
+      @member_class = member_class
+      register_parent_data
+    end
+
+    # Syntactic sugar method for returning collection
+    #
+    # @example
+    #   all # returns collection
+    #
+    # @return [self]
+    #
+    # @api public
+    def all
+      self
+    end
+
+    # Initializes new {member_class} with `params`
+    #
+    # - Ensures a parent id is meged into `params` (see #default_params).
+    # - Defines method `#save` on new collection member
+    # - Adds new item to collection
+    #
+    # @example usage
+    #
+    #   >> person = person = BlockScore::Person.retrieve('55de4af7643735000300000f')
+    #   >> person.question_sets.new
+    #   => #<BlockScore::QuestionSet:0x3fc67902f1b4 JSON:{
+    #     "person_id": "55de4af7643735000300000f"
+    #   }>
+    #
+    # @param params [Hash] initial params for member
+    #
+    # @return instance of {member_class}
+    #
+    # @api public
+    def new(params = {})
+      attributes = params.merge(default_params)
+      instance   = member_class.new(attributes)
+
+      new_member(instance) do |member|
+        self << member
+      end
+    end
+
+    # Relaod the contents of the collection
+    #
+    # @example usage
+    #   person.question_sets.refresh # => [#<BlockScore::QuestionSet...]
+    #
+    # @return [self]
+    #
+    # @api public
+    def refresh
+      clear
+      register_parent_data
+      self
     end
 
-    def respond_to?(method, include_all = false)
-      @target.respond_to?(method, include_all)
+    # Name of parent resource
+    #
+    # @example
+    #   self.parent_name # => 'person'
+    #
+    # @return [String]
+    #
+    # @api semipublic
+    def parent_name
+      parent.class.resource
+    end
+
+    # Initialize a collection member and save it
+    #
+    # @example
+    #   >> person.question_sets.create
+    #   => #<BlockScore::QuestionSet:0x3fc67a6007f4 JSON:{
+    #     "object": "question_set",
+    #     "id": "55ef5d5b62386200030001b3",
+    #     "created_at": 1441750363,
+    #     ...
+    #     }
+    #
+    # @param params [Hash] params
+    #
+    # @return new saved instance of {member_class}
+    #
+    # @api public
+    def create(params = {})
+      fail Error, 'Create parent first' unless parent.id
+      assoc_params = default_params.merge(params)
+      instance = member_class.create(assoc_params)
+
+      new_member(instance) do |member|
+        register_to_parent(member)
+      end
+    end
+
+    # Retrieve a collection member by its id
+    #
+    # @example usage
+    #   person.question_sets.retrieve('55ef5b4e3532630003000178') # => instance of QuestionSet
+    #
+    # @param id [String] resource id
+    #
+    # @return instance of {member_class} if found
+    # @raise [BlockScore::NotFoundError] otherwise
+    #
+    # @api public
+    def retrieve(id)
+      each do |item|
+        next unless item.id == id
+        return item
+      end
+
+      instance = member_class.retrieve(id)
+
+      new_member(instance) do |member|
+        register_to_parent(member)
+      end
+    end
+
+    protected
+
+    # @!attribute [r] member_class
+    # class which will be used for the embedded
+    # resources in the collection
+    #
+    # @return [Class]
+    #
+    # @api private
+    attr_reader :member_class
+
+    # Default params for making an instance of {member_class}
+    #
+    # @return [Hash]
+    #
+    # @api private
+    def default_params
+      {
+        foriegn_key => parent.id
+      }
     end
 
     private
 
-    def method_missing(method, *args, &block)
-      @target.public_send(method, *args, &block)
+    # Generate foriegn key name for parent resource
+    #
+    # @return [Symbol] resource name as id
+    #
+    # @api private
+    def foriegn_key
+      :"#{parent_name}_id"
+    end
+
+    # Initialize a new collection member
+    #
+    # @param instance [BlockScore::Base] collection member instance
+    # @yield [Member] initialized member
+    #
+    # @return [Member] new member
+    #
+    # @api private
+    def new_member(instance, &blk)
+      Member.new(parent, instance).tap(&blk)
+    end
+
+    # Check if `parent_id` is defined on `item`
+    #
+    # @param item [BlockScore::Base] any resource
+    #
+    # @return [Boolean]
+    #
+    # @api private
+    def parent_id?(item)
+      parent.id && item.send(foriegn_key) == parent.id
+    end
+
+    # Register a resource in collection
+    #
+    # @param item [BlockScore::Base] a resource
+    #
+    # @raise [BlockScore::Error] if no `parent_id`
+    # @return [BlockScore::Base] otherwise
+    #
+    # @api private
+    def register_to_parent(item)
+      fail Error, 'None belonging' unless parent_id?(item)
+      ids << item.id
+      self << item
+      item
+    end
+
+    # Fetches embedded ids from parent and adds to self
+    #
+    # @return [undefined]
+    #
+    # @api private
+    def register_parent_data
+      ids.each do |id|
+        item = member_class.retrieve(id)
+        self << item
+      end
+    end
+
+    # ids that belong to the collection
+    #
+    # @return [Array<String>]
+    #
+    # @api private
+    def ids
+      parent.attributes.fetch(:"#{Util.to_plural(member_class.resource)}", [])
     end
   end
 end
diff --git a/lib/blockscore/collection/member.rb b/lib/blockscore/collection/member.rb
new file mode 100644
index 0000000..ff50e08
--- /dev/null
+++ b/lib/blockscore/collection/member.rb
@@ -0,0 +1,100 @@
+module BlockScore
+  class Collection
+    # Member of a {Collection} class
+    class Member < SimpleDelegator
+      # Initialize a new member
+      #
+      # @param parent [BlockScore::Base] parent resource
+      # @param instance [BlockScore::Base] member instance
+      #
+      # @return [undefined]
+      #
+      # @api private
+      def initialize(parent, instance)
+        @instance = instance
+        @parent = parent
+
+        super(instance)
+      end
+
+      # Save parent, set parent id, and save instance
+      #
+      # @example
+      #   # saves both unsaved person and unsaved question_set
+      #   person = Person.new(attributes)
+      #   question_set = QuestionSet.new
+      #   Member.new(person, question_set).save
+      #
+      # @return return value of instance `#save`
+      #
+      # @api public
+      def save
+        save_parent
+        send(:"#{parent_name}_id=", parent.id)
+        result = instance.save
+        ids.push(instance.id) unless ids.include?(instance.id)
+        result
+      end
+
+      private
+
+      # Name of parent resource
+      #
+      # @example
+      #   self.parent_name # => 'person'
+      #
+      # @return [String]
+      #
+      # @api private
+      def parent_name
+        parent.class.resource
+      end
+
+      # Save parent if it hasn't already been saved
+      #
+      # @return return of parent.save if previously unsaved
+      # @return nil otherwise
+      #
+      # @api private
+      def save_parent
+        parent.save unless parent_saved?
+      end
+
+      # Check if parent is saved
+      #
+      # @return [Boolean]
+      #
+      # @api private
+      def parent_saved?
+        parent.id
+      end
+
+      # @!attribute [r] instance
+      # member instance methods are delegated to
+      #
+      # @return [BlockScore::Base]
+      #
+      # @api private
+      attr_reader :instance
+
+      # @!attribute [r] parent
+      # collection parent the collectino conditionally updates
+      #
+      # @return [BlockScore::Base]
+      #
+      # @api private
+      attr_reader :parent
+
+      private
+
+      # ids that belong to associated parent resource
+      #
+      # @return [Array<String>]
+      #
+      # @api private
+      def ids
+        parent.attributes.fetch(:"#{Util.to_plural(instance.class.resource)}", [])
+      end
+    end
+  end
+end
diff --git a/lib/blockscore/connection.rb b/lib/blockscore/connection.rb
index ade3d24..9d1c5df 100644
--- a/lib/blockscore/connection.rb
+++ b/lib/blockscore/connection.rb
@@ -32,7 +32,7 @@ def request(method, path, params)
       begin
         response = execute_request(method, path, params)
       rescue SocketError, Errno::ECONNREFUSED => e
-        fail APIConnectionError, e.message
+        raise APIConnectionError, e.message
       end
 
       Response.handle_response(resource, response)
@@ -55,7 +55,7 @@ def execute_request(method, path, params)
 
     def encode_path_params(path, params)
       encoded = URI.encode_www_form(params)
-      [path, encoded].join("?")
+      [path, encoded].join('?')
     end
   end
 end
diff --git a/lib/blockscore/errors/api_error.rb b/lib/blockscore/errors/api_error.rb
index 1b9bd6b..43a6d0d 100644
--- a/lib/blockscore/errors/api_error.rb
+++ b/lib/blockscore/errors/api_error.rb
@@ -15,7 +15,7 @@ class APIError < Error
     # APIError - Indicates an error on the server side (HTTP 5xx)
     # AuthenticationError - Indicates an authentication error (HTTP 401)
     def initialize(response)
-      body = JSON.parse(response.body, :symbolize_names => true)
+      body = JSON.parse(response.body, symbolize_names: true)
 
       @message = body[:error][:message]
       @http_status = response.code
@@ -24,8 +24,8 @@ def initialize(response)
     end
 
     def to_s
-      status_string = @http_status ? "(Status: #{@http_status})" : ""
-      type_string = @error_type ? "(Type: #{@error_type})" : ""
+      status_string = @http_status ? "(Status: #{@http_status})" : ''
+      type_string = @error_type ? "(Type: #{@error_type})" : ''
 
       "#{type_string} #{@message} #{status_string}"
     end
diff --git a/lib/blockscore/errors/invalid_request_error.rb b/lib/blockscore/errors/invalid_request_error.rb
index f76873e..e7ff856 100644
--- a/lib/blockscore/errors/invalid_request_error.rb
+++ b/lib/blockscore/errors/invalid_request_error.rb
@@ -19,9 +19,9 @@ def initialize(response)
     end
 
     def to_s
-      status_string = @http_status ? "(Status: #{@http_status})" : ""
-      type_string = @error_type ? "(Type: #{@error_type})" : ""
-      param_string = @param ? "(#{@param})" : ""
+      status_string = @http_status ? "(Status: #{@http_status})" : ''
+      type_string = @error_type ? "(Type: #{@error_type})" : ''
+      param_string = @param ? "(#{@param})" : ''
 
       "#{type_string} #{@message} #{param_string} #{status_string}"
     end
diff --git a/lib/blockscore/person.rb b/lib/blockscore/person.rb
index ec311a7..b26e3a4 100644
--- a/lib/blockscore/person.rb
+++ b/lib/blockscore/person.rb
@@ -11,7 +11,7 @@ class Person < Base
 
     def initialize(options = {})
       super
-      @question_sets = Collection.new(QuestionSet.new(person: self))
+      @question_sets = Collection.new(self, QuestionSet)
     end
 
     def valid?
diff --git a/lib/blockscore/question_set.rb b/lib/blockscore/question_set.rb
index 944230d..c79ab0c 100644
--- a/lib/blockscore/question_set.rb
+++ b/lib/blockscore/question_set.rb
@@ -6,14 +6,7 @@ class QuestionSet < Base
     include BlockScore::Actions::Retrieve
     include BlockScore::Actions::All
 
-    def_delegators 'self.class', :retrieve, :all, :post, :endpoint
-
-    def create
-      result = self.class.create(person_id: person.id)
-      person.question_sets << result.id
-
-      result
-    end
+    def_delegators 'self.class', :post, :endpoint
 
     def score(answers = nil)
       if answers.nil? && attributes
diff --git a/lib/blockscore/util.rb b/lib/blockscore/util.rb
index 3624aeb..6c5cf6e 100644
--- a/lib/blockscore/util.rb
+++ b/lib/blockscore/util.rb
@@ -11,13 +11,13 @@ module Util
     }
 
     def parse_json!(json_obj)
-      JSON.parse(json_obj, :symbolize_names => true)
+      JSON.parse(json_obj, symbolize_names: true)
     end
 
     def parse_json(json_obj)
       parse_json! json_obj
     rescue JSON::ParserError
-      fail Error, "An error has occurred. If this problem persists, please message support@blockscore.com."
+      raise Error, 'An error has occurred. If this problem persists, please message support@blockscore.com.'
     end
 
     def create_object(resource, options = {})
@@ -65,16 +65,16 @@ def to_constant(camel_cased_word)
     end
 
     def to_camelcase(str)
-      str.split('_').map { |i| i.capitalize }.join('')
+      str.split('_').map(&:capitalize).join('')
     end
 
     # Taken from Rulers: http://git.io/vkWqf
     def to_underscore(str)
-      str.gsub(/::/, '/').
-      gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
-      gsub(/([a-z\d])([A-Z])/,'\1_\2').
-      tr("-", "_").
-      downcase
+      str.gsub(/::/, '/')
+        .gsub(/([A-Z]+)([A-Z][a-z])/, '\1_\2')
+        .gsub(/([a-z\d])([A-Z])/, '\1_\2')
+        .tr('-', '_')
+        .downcase
     end
   end
 end
diff --git a/lib/blockscore/version.rb b/lib/blockscore/version.rb
index 26e1366..5f17869 100644
--- a/lib/blockscore/version.rb
+++ b/lib/blockscore/version.rb
@@ -1,3 +1,3 @@
 module BlockScore
-  VERSION = '4.1.2'.freeze
-end
\ No newline at end of file
+  VERSION = '4.2.0'.freeze
+end
diff --git a/spec/factories.rb b/spec/factories.rb
index 77209c3..c5d8b45 100644
--- a/spec/factories.rb
+++ b/spec/factories.rb
@@ -9,10 +9,10 @@ def initialize
 
   delegate :association, to: :@strategy
 
-  def result(evaluation)
+  def result(evaluation, attrs = {})
     compiled = @strategy.result(evaluation)
     case compiled
-    when BlockScore::Base then compiled.attributes.to_json
+    when BlockScore::Base then compiled.attributes.merge(attrs).to_json
     when Hash             then compiled.to_json
     else
       fail ArgumentError, "don't know how to handle type #{evaluation.class.inspect}"
@@ -38,6 +38,10 @@ def full_address
   "#{street} #{city} #{country}"
 end
 
+def resource_id
+  Faker::Number.hexadecimal(24)
+end
+
 FactoryGirl.define do
   # Each response has this metadata so we define it as a trait
   trait :metadata do
@@ -175,6 +179,29 @@ def full_address
     details { build(:company_details) }
   end
 
+  factory :fake_member, class: 'BlockScore::FakeResource' do
+    object { 'fake_member' }
+    transient do
+      given_id resource_id
+      parent_id resource_id
+    end
+
+    id { given_id }
+    fake_resource_id { parent_id }
+  end
+
+  factory :fake_resource, class: 'BlockScore::FakeResource' do
+    object { 'fake_resource' }
+    metadata
+    transient { members_count 2 }
+
+    fake_resources do
+      members_count.times.map do
+        resource_id
+      end
+    end
+  end
+
   factory :person_params, class: 'BlockScore::Person' do
     name
     document
@@ -186,6 +213,7 @@ def full_address
 
   factory :person, class: 'BlockScore::Person' do
     skip_create
+    transient { question_sets_count 1 }
 
     object { 'person' }
     metadata
@@ -199,15 +227,20 @@ def full_address
     address
     document
     details { build(:person_details) }
+
     question_sets do
-      rand(0..5).times.collect { Faker::Base.regexify(/\d{24}/) }
+      question_sets_count.times.map do
+        resource_id
+      end
     end
+
+    initialize_with { new(attributes) }
   end
 
   # QuestionSet Factory
 
   factory :question_set_params, class: 'BlockScore::QuestionSet' do
-    person_id { Faker::Base.regexify(/\d{24}/) }
+    person_id { resource_id }
   end
 
   factory :question_set, class: 'BlockScore::QuestionSet' do
@@ -217,7 +250,7 @@ def full_address
     metadata
     timestamps
     testmode
-    person_id { Faker::Base.regexify(/\d{24}/) }
+    person_id { resource_id }
     score { rand * 100 }
     expired { false }
     time_limit { rand(120..360) }
@@ -303,7 +336,7 @@ def full_address
   # We can do this because the error type is determined by the
   # HTTP response code.
   factory :blockscore_error, class: Hash, traits: [:resource] do
-    ignore do
+    transient do
       error_type 'api_error'
     end
 
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index cab1adf..fbfd78a 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -5,6 +5,7 @@
 require 'webmock'
 require 'webmock/rspec'
 require 'rspec'
+require 'rspec/its'
 
 BlockScore::Spec.setup
 
diff --git a/spec/support/stubbed_request.rb b/spec/support/stubbed_request.rb
index ee29519..4f1428d 100644
--- a/spec/support/stubbed_request.rb
+++ b/spec/support/stubbed_request.rb
@@ -5,6 +5,12 @@ def initialize(request)
       @uri     = request.uri
     end
 
+    def body
+      JSON.parse(request.body)
+    rescue
+      nil
+    end
+
     def factory_name
       resource.singularize
     end
diff --git a/spec/support/stubbed_response.rb b/spec/support/stubbed_response.rb
index 61fca05..9bce4dc 100644
--- a/spec/support/stubbed_response.rb
+++ b/spec/support/stubbed_response.rb
@@ -94,7 +94,7 @@ def response
       private
 
       def factory_response
-        json(factory_name)
+        json(factory_name, request.body)
       end
     end
 
diff --git a/spec/unit/blockscore/actions_spec.rb b/spec/unit/blockscore/actions_spec.rb
index 23d63d7..c3aa3c7 100644
--- a/spec/unit/blockscore/actions_spec.rb
+++ b/spec/unit/blockscore/actions_spec.rb
@@ -42,8 +42,18 @@ module BlockScore
       let(:route) { 'https://api.blockscore.com/fake_resources/abc123' }
 
       it 'uses the correct endpoint' do
-        should receive(:request).with(:get, route, {}).once
-        mock.retrieve('abc123')
+        should receive(:request).with(:get, route, {}).once { resource }
+        mock.retrieve('abc123').attributes
+      end
+
+      context 'when id is invalid' do
+        pending 'should raise not found if not a resource style id' do
+          expect { mock.retrieve('bad_id') }.to raise_error(NotFoundError)
+        end
+
+        it 'should raise ArgumentError if empty' do
+          expect { mock.retrieve('') }.to raise_error(ArgumentError)
+        end
       end
     end
 
diff --git a/spec/unit/blockscore/candidate_spec.rb b/spec/unit/blockscore/candidate_spec.rb
index 3ef3a2f..bde5e3a 100644
--- a/spec/unit/blockscore/candidate_spec.rb
+++ b/spec/unit/blockscore/candidate_spec.rb
@@ -32,7 +32,7 @@ module BlockScore
       subject(:search) { -> { candidate.search(constraints) } }
 
       context 'search request' do
-        let(:uri)      { "/watchlists"                                         }
+        let(:uri)      { '/watchlists'                                         }
         let(:body)     { { 'candidate_id' => candidate.id }.merge(constraints) }
         let(:expected) { { body: hash_including(body) }                        }
         before { search.call }
diff --git a/spec/unit/blockscore/collection_spec.rb b/spec/unit/blockscore/collection_spec.rb
new file mode 100644
index 0000000..1ed9cd0
--- /dev/null
+++ b/spec/unit/blockscore/collection_spec.rb
@@ -0,0 +1,178 @@
+module BlockScore
+  RSpec.describe Collection do
+    let(:parent) { create(:fake_resource) }
+    let(:member_class) { FakeResource }
+    let(:collection) { Collection.new(parent, member_class) }
+
+    before do
+      Util::PLURAL_LOOKUP['fake_resource'] = 'fake_resources'
+      allow(member_class).to receive(:create) { create(:fake_member, parent_id: parent.id) }
+    end
+
+    describe '#all' do
+      subject { collection.all  }
+
+      it 'should return self' do
+        is_expected.to be(collection)
+      end
+    end
+
+    describe '#create' do
+      let(:created) { create(:fake_member, parent_id: parent.id) }
+      subject { collection.create }
+      before(:each) do
+        allow(member_class).to receive(:create) { created }
+      end
+
+      it 'should send merged default and arg params' do
+        foriegn_key = :"#{parent.class.resource}_id"
+        expect(member_class).to receive(:create).with(foriegn_key => parent.id, foo_param: 'bar_attr')
+        collection.create(foo_param: 'bar_attr')
+      end
+
+      it 'should update ids in Parent#attributes' do
+        expect(parent.attributes[:fake_resources]).to include(subject.id)
+      end
+
+      it 'should add to collection' do
+        expect(collection).to include(subject)
+      end
+
+      it 'should error if parent not created' do
+        parent = FakeResource.new
+        collection = Collection.new(parent, member_class)
+        expect { collection.create }.to raise_error(Error, 'Create parent first')
+      end
+
+      it 'should retrieve item from registered' do
+        found_qs = collection.retrieve(subject.id)
+        expect(subject).to eq(found_qs)
+      end
+    end
+
+    describe '#new' do
+      subject { collection.new }
+
+      it 'should add to collection' do
+        count = collection.size
+        result = collection.new
+        expect(collection.size).to eq(count + 1)
+        expect(collection).to include(result)
+      end
+
+      context 'when saving' do
+        it 'should have parent#id after saving' do
+          subject.fake_resource_id = 'some_id'
+          subject.save
+          expect(subject.fake_resource_id).to eq(parent.id)
+        end
+
+        it 'should be retrievable after' do
+          collection.create
+          subject.save
+          collection.create
+          expect(collection.retrieve(subject.id)).to be(subject)
+        end
+      end
+    end
+
+    describe '#retrieve' do
+      context 'when in person#attributes' do
+        let(:parent) { create(:fake_resource) }
+        let(:existing_id) { parent.attributes[:fake_resources].last }
+        subject { collection.retrieve(existing_id) }
+
+        it 'should retrieve correctly' do
+          last = collection.last
+          expect(subject).to eq(last)
+          expect(subject.id).to eq(existing_id)
+        end
+
+        it 'checks collect' do
+          expect(collection).to receive(:each).and_call_original
+          collection.retrieve(existing_id)
+        end
+      end
+
+      context 'when not in person#attributes' do
+        let(:parent) { create(:fake_resource, members_count: 0) }
+        let(:collection) { Collection.new(parent, member_class) }
+        let(:item) { create(:fake_member, parent_id: parent.id) }
+        let(:data) { parent.attributes.fetch(:fake_resources) }
+        subject { collection.retrieve(item.id) }
+
+        before(:each) do
+          allow(member_class).to receive(:retrieve).with(item.id) { item }
+        end
+
+        it 'uses member_class.retrieve' do
+          expect(member_class).to receive(:retrieve).with(item.id).and_return(item)
+          expect(collection.retrieve(item.id)).to eq(item)
+        end
+
+        it 'registers new question set' do
+          aggregate_failures('for person and collection') do
+            expect(collection).to receive(:<<).and_call_original
+            expect(data).to receive(:<<).with(item.id).and_call_original
+          end
+          collection.retrieve(item.id)
+        end
+
+        it 'errors if not belonging' do
+          item.fake_resource_id = 'some_not_associated_id'
+          expect { subject }.to raise_error(Error, 'None belonging')
+        end
+      end
+    end
+
+    describe '#refresh' do
+      subject { collection }
+      let(:item) { member_class.create }
+      before(:each) { parent.attributes[:fake_resources] << item.id }
+
+      # refactor
+      it 'should register new data from parent' do
+        parent.attributes[:fake_resources].clear
+        parent.attributes[:fake_resources].push(item.id)
+        expect(member_class).to receive(:retrieve).with(item.id).at_least(:twice).and_call_original
+        subject.refresh
+      end
+
+      it 'should clear and reload' do
+        expect(subject).to receive(:clear).and_call_original
+        expect(subject).to receive(:register_parent_data).and_call_original
+        result = subject.refresh
+        expect(subject).to be(result)
+      end
+
+      context 'when creating' do
+        it 'should be included in refresh' do
+          result = subject.create
+          subject.refresh
+          expect(subject.map(&:id)).to include(result.id)
+        end
+
+        it 'should include saved in refresh' do
+          item = FakeResource.new(fake_resource_id: parent.id)
+          allow(member_class).to receive(:new) { item }
+          allow(item).to receive(:save) { create(:fake_member, parent_id: parent.id) }
+          result = subject.new
+          result.save
+          subject.refresh
+          expect(subject.map(&:id)).to include(result.id)
+        end
+      end
+
+      context 'when retrieving belonging' do
+        it 'should be included in refresh' do
+          item = create(:fake_resource)
+          item.parent_id = parent.id
+          allow(member_class).to receive(:retrieve) { item }
+          result = subject.retrieve(item.id)
+          subject.refresh
+          expect(subject.map(&:id)).to include(result.id)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/unit/blockscore/member_spec.rb b/spec/unit/blockscore/member_spec.rb
new file mode 100644
index 0000000..3b88b57
--- /dev/null
+++ b/spec/unit/blockscore/member_spec.rb
@@ -0,0 +1,104 @@
+module BlockScore
+  RSpec.describe Collection::Member do
+    let(:parent) { create(:fake_resource) }
+    let(:member_class) { FakeResource }
+    let(:collection) { Collection.new(parent, member_class) }
+
+    before do
+      Util::PLURAL_LOOKUP['fake_resource'] = 'fake_resources'
+      allow(member_class).to receive(:create) { create(:fake_member, parent_id: parent.id) }
+    end
+
+    context 'when saving' do
+      let(:member_class) { FakeResource                         }
+      let(:parent)       { FakeResource.new                     }
+      let(:collection)   { Collection.new(parent, member_class) }
+      subject(:member)   { collection.new                       }
+
+      context 'when parent is not persisted' do
+        before { allow(parent).to receive(:save).and_call_original }
+
+        it { expect(member.save).to be(true) }
+
+        it do
+          member.save
+          expect(parent).to have_received(:save).once
+        end
+
+        context 'after saving' do
+          before { member.save }
+          let(:member_parent_id) { member.fake_resource_id }
+
+          it { is_expected.to be_persisted }
+          it { expect(parent).to be_persisted }
+          it { expect(member_parent_id).to eql(parent.id) }
+        end
+      end
+
+      it 'should not save persisted parent' do
+        parent.save
+
+        aggregate_failures('when saving') do
+          expect(parent).not_to receive(:save)
+          expect(member.save).to be(true)
+        end
+
+        aggregate_failures('after saving') do
+          expect(member.persisted?).to be(true)
+          expect(parent.persisted?).to be(true)
+          foriegn_key = :"#{parent.class.resource}_id"
+          expect(member.send(foriegn_key)).to eq(parent.id)
+        end
+      end
+
+      it 'should not add to parent if existing' do
+        member.save
+        embedded_resource = :"#{Util.to_plural(parent.class.resource)}"
+        tracked_ids = parent.send(embedded_resource)
+        size = tracked_ids.size
+        member.save
+        expect(size).to eql(size)
+        expect(tracked_ids).to include(member.id)
+      end
+    end
+
+    context 'when created' do
+      let(:created) { create(:fake_member, parent_id: parent.id) }
+      subject { collection.create }
+      before(:each) do
+        allow(member_class).to receive(:create) { created }
+      end
+
+      it 'should have the Parent#id' do
+        expect(member_class).to receive(:create).with(fake_resource_id: parent.id).and_call_original
+        subject
+      end
+    end
+
+    context 'when instantiating a new' do
+      subject { collection.new }
+
+      it 'should delegate to member_class' do
+        # odd bug... test fails when replaced with parent.id
+        args = { fake_resource_id: collection.parent.id }
+        expect(member_class).to receive(:new).with(args).and_call_original
+        collection.new
+      end
+
+      it 'should save parent if not persisted' do
+        parent = create(:fake_resource)
+        parent.id = nil
+        collection = Collection.new(parent, member_class)
+        item = collection.new
+        expect(parent).to receive(:save).and_call_original
+        item.save
+      end
+
+      it 'should have Parent#id' do
+        subject.person_id = 'some_id'
+        subject.save
+        expect(subject.fake_resource_id).to eq(collection.parent.id)
+      end
+    end
+  end
+end
diff --git a/spec/unit/blockscore/person_spec.rb b/spec/unit/blockscore/person_spec.rb
index ae72825..a840832 100644
--- a/spec/unit/blockscore/person_spec.rb
+++ b/spec/unit/blockscore/person_spec.rb
@@ -3,6 +3,30 @@ module BlockScore
     let(:api_stub) { @api_stub }
     let(:action) { -> { create(:person).details } }
 
+    context 'when person has existing question sets' do
+      let(:person) { create(:person, question_set_count: 1) }
+      subject(:question_sets) { person.question_sets }
+      its(:size) { should eql(1) }
+      its(:ids) { should be(person.attributes[:question_sets]) }
+      its(:first) { should be_an_instance_of(QuestionSet) }
+
+      it 'should load attributes' do
+        expect(question_sets.first.attributes).not_to be(nil)
+      end
+    end
+
+    it '#persisted?' do
+      persisted_person = create(:person)
+      new_person = Person.new
+      expect(persisted_person.persisted?).to be(true)
+      expect(new_person.persisted?).to be(false)
+    end
+
+    it '#id' do
+      person = create(:person)
+      expect(person.id).not_to be(nil)
+    end
+
     it '#valid?' do
       person = create(:person, status: 'valid')
       expect(person.valid?).to eq(true)
diff --git a/spec/unit/blockscore/question_set_spec.rb b/spec/unit/blockscore/question_set_spec.rb
index d498205..e2feac6 100644
--- a/spec/unit/blockscore/question_set_spec.rb
+++ b/spec/unit/blockscore/question_set_spec.rb
@@ -1,61 +1,41 @@
 module BlockScore
   RSpec.describe QuestionSet do
-    let(:api_stub) { @api_stub }
     let(:person) { create(:person_params) }
 
-    it 'create' do
-      person.question_sets.count
-      person.question_sets.create
-      assert_requested(api_stub, times: 2)
-    end
-
-    it 'create question_set count' do
-      count = person.question_sets.count
-      person.question_sets.create
-      expect(count + 1).to be_truthy
-      assert_requested(api_stub, times: 2)
-    end
-
-    it 'retrieve' do
-      qs = person.question_sets.create
-      person.question_sets.retrieve(qs.id)
-      assert_requested(api_stub, times: 3)
-    end
-
-    describe '#all' do
-      it 'requests' do
-        person.question_sets.all
-        assert_requested(api_stub, times: 2)
-      end
-
-      it ':count' do
-        response = person.question_sets.all(count: 2)
-        expect(response.count).to eq(2)
-        assert_requested(api_stub, times: 2)
-      end
-
-      it ':offset' do
-        response = person.question_sets.all(count: 2, offset: 2)
-        expect(response.count).to eq(2)
-        assert_requested(api_stub, times: 2)
-      end
-    end
-
-    describe '#score' do
-      let(:answers) do
-        [
-          { question_id: 1, answer_id: 1 },
-          { question_id: 2, answer_id: 1 },
-          { question_id: 3, answer_id: 1 },
-          { question_id: 4, answer_id: 1 },
-          { question_id: 5, answer_id: 1 }
-        ]
+    describe 'api requests' do
+      let(:api_stub) { @api_stub }
+
+      context 'when creating' do
+        it 'create' do
+          person.question_sets.count
+          person.question_sets.create
+          assert_requested(api_stub, times: 2)
+        end
+
+        it 'create question_set count' do
+          count = person.question_sets.count
+          person.question_sets.create
+          expect(count + 1).to be_truthy
+          assert_requested(api_stub, times: 2)
+        end
       end
 
-      it 'score call does request' do
-        qs = person.question_sets.create
-        qs.score(answers)
-        assert_requested(api_stub, times: 3)
+      context 'when scoring' do
+        let(:answers) do
+          [
+            { question_id: 1, answer_id: 1 },
+            { question_id: 2, answer_id: 1 },
+            { question_id: 3, answer_id: 1 },
+            { question_id: 4, answer_id: 1 },
+            { question_id: 5, answer_id: 1 }
+          ]
+        end
+
+        it 'score call does request' do
+          qs = person.question_sets.create
+          qs.score(answers)
+          assert_requested(api_stub, times: 3)
+        end
       end
     end
   end