Recent work has documented a wide range of important psychological differences across societies. Multiple explanations have been offered for why such differences exist, including historical philosophies, subsistence methods, social mobility, social class, climactic stresses, and religion. With the growing body of theory and data, there is an emerging need for an organizing framework. We propose here that a behavioral ecological perspective, particularly the idea of adaptive phenotypic plasticity, can provide an overarching framework for thinking about psychological variation across cultures and societies. We focus on how societies vary as a function of six important ecological dimensions: density, relatedness, sex ratio, mortality likelihood, resources, and disease. This framework can: (a) highlight new areas of research, (b) integrate and ground existing cultural psychological explanations, (c) integrate research on variation across human societies with research on parallel variations in other animal species, (d) provide a way for thinking about multiple levels of culture and cultural change, and (e) facilitate the creation of an ecological taxonomy of societies, from which one can derive specific predictions about cultural differences and similarities. Finally, we discuss the relationships between the current framework and existing perspectives.