To recognize that human beings are adapted for social living is fundamental to the science of human psychology. I argue that the development of broad social psychological theory would benefit from taking this basic premise more seriously. We need to pay more attention to the implications for personality and social psychology of recognizing that all of the building blocks of human psychology--cognition, emotion, motivation--have been shaped by the demands of social interdependence. In this article I illustrate the generative potential of this basic premise for development of more expansive social theory.