diff --git a/.travis.yml b/.travis.yml
index b6b28e9038..afc860a58f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -18,10 +18,10 @@ install:
 - >
   conda create -q -c synthicity -n test-environment
   python=$TRAVIS_PYTHON_VERSION
-  ipython-notebook jinja2 matplotlib numpy pandas pandana patsy pip pytables
-  pytest pyyaml scipy statsmodels toolz
+  cytoolz ipython-notebook jinja2 matplotlib numpy pandas pandana patsy pip
+  pytables pytest pyyaml scipy statsmodels toolz
 - source activate test-environment
-- pip install simplejson bottle prettytable
+- pip install bottle prettytable simplejson zbox
 - pip install https://github.com/synthicity/urbansim/archive/master.zip
 - pip install openmatrix
 - pip install pytest-cov coveralls pep8
diff --git a/activitysim/activitysim.py b/activitysim/activitysim.py
index 580663396a..4dc54907b1 100644
--- a/activitysim/activitysim.py
+++ b/activitysim/activitysim.py
@@ -2,13 +2,14 @@
 # Copyright (C) 2014-2015 Synthicity, LLC
 # See full license in LICENSE.txt.
 
-from skim import Skims, Skims3D
+from operator import itemgetter
 
 import numpy as np
 import pandas as pd
-
 from urbansim.urbanchoice import interaction
+from zbox import toolz as tz
 
+from .skim import Skims, Skims3D
 from .mnl import utils_to_probs, make_choices
 
 
@@ -264,3 +265,41 @@ def interaction_simulate(
     choices = model_design.index.take(positions + offsets)
 
     return pd.Series(choices, index=choosers.index), model_design
+
+
+def other_than(groups, bools):
+    """
+    Construct a Series that has booleans indicating the presence of
+    something- or someone-else with a certain property within a group.
+
+    Parameters
+    ----------
+    groups : pandas.Series
+        A column with the same index as `bools` that defines the grouping
+        of `bools`. The `bools` Series will be used to index `groups` and
+        then the grouped values will be counted.
+    bools : pandas.Series
+        A boolean Series indicating where the property of interest is present.
+        Should have the same index as `groups`.
+
+    Returns
+    -------
+    others : pandas.Series
+        A boolean Series with the same index as `groups` and `bools`
+        indicating whether there is something- or something-else within
+        a group with some property (as indicated by `bools`).
+
+    """
+    counts = groups[bools].value_counts()
+    merge_col = groups.to_frame(name='right')
+    pipeline = tz.compose(
+        tz.curry(pd.Series.fillna, value=False),
+        itemgetter('left'),
+        tz.curry(
+            pd.DataFrame.merge, right=merge_col, how='right', left_index=True,
+            right_on='right'),
+        tz.curry(pd.Series.to_frame, name='left'))
+    gt0 = pipeline(counts > 0)
+    gt1 = pipeline(counts > 1)
+
+    return gt1.where(bools, other=gt0)
diff --git a/activitysim/tests/test_other_than.py b/activitysim/tests/test_other_than.py
new file mode 100644
index 0000000000..d607886b01
--- /dev/null
+++ b/activitysim/tests/test_other_than.py
@@ -0,0 +1,25 @@
+import pandas as pd
+import pandas.util.testing as pdt
+import pytest
+
+
+from ..activitysim import other_than
+
+
+@pytest.fixture(scope='module')
+def people():
+    return pd.DataFrame({
+        'household': [1, 2, 2, 3, 3, 3, 4, 4, 4, 4],
+        'ptype':     [1, 2, 1, 3, 1, 2, 3, 2, 2, 1]},
+        index=['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j'])
+
+
+def test_other_than(people):
+    expected = pd.Series(
+        [False, False, True, True, True, False, True, True, True, True],
+        index=people.index)
+
+    bools = people['ptype'] == 2
+    others = other_than(people['household'], bools)
+
+    pdt.assert_series_equal(others, expected)
diff --git a/setup.py b/setup.py
index 53aeb9c4fd..2001d26ccd 100644
--- a/setup.py
+++ b/setup.py
@@ -18,10 +18,12 @@
     ],
     packages=find_packages(exclude=['*.tests']),
     install_requires=[
-        'numpy>=1.8.0',
-        'openmatrix>=0.2.2',
-        'pandas>=0.13.1',
-        'tables>=3.1.0',
-        'urbansim>=1.3'
+        'numpy >= 1.8.0',
+        'openmatrix >= 0.2.2',
+        'pandas >= 0.13.1',
+        'tables >= 3.1.0',
+        'toolz >= 0.7',
+        'urbansim >= 1.3',
+        'zbox >= 1.2'
     ]
 )