Consumers make multi-category decisions in a variety of contexts such as choice of multiple categories during a shopping trip. While complementarity gives managers some control over consumers' buying behavior, co-occurrence or co-incidence is less controllable. Other acts that may affect multi-category choice may be household preferences or household demographics. Not accounting for these 3 factors simultaneously could lead to erroneous inferences. A conceptual framework that incorporates complimentarity, co-incidence and heterogeneity as the factors that could lead to multi-category choice is developed. This framework is then translated into a model of multi-category choice.