The Atlas of Interpersonal Situations provides a systematic theoretical account for understanding the impact of situations on patterns of social interaction. Structured around descriptions of twenty-one of the most common situations that people encounter in everyday life, the authors aim to provide readers with the tools needed to understand how those situations influence interpersonal behavior. These descriptions are intended to be freestanding, each one providing analysis, research examples, and everyday descriptions of the prototypical situation. The authors build upon the tools of interdependence theory, which stresses the manner in which people’s outcomes are determined by the structure of their interaction with each other. This analysis makes clear exactly what is ‘social’ about ‘social psychology’.