The problem of how people come to organize and comprehend the information contained in another person's continuous or ongoing stream of behavior is an issue that is of fundamental importance to several areas of psychology. These include social, cognitive, and clinical as well as to other disciplines such as sociology, communication, and political science whose focus is also concerned with issues related to the nature of social action and interaction. Despite this fact relatively little theory and research has been devoted to the behavior perception problem. The overall goal of this research is to further illuminate the nature of the behavior perception process and at the same time establish its prominent role in a variety of psychological phenomena. More specifically, several causes and effects of variation in how an individual divides or utilizes another person's ongoing behavior into meaningful actions will be explored. An initial set of studies examines the relationship between the number of actions perceivers divide a behavior sequence into (i.e., their utilization rate) and their subsequent memory for the action.related details of that sequence. A second set of studies examines the relationship between utilization rate and causal attribution. A final set of studies examines the relationship between utilization rate and affect. The studies will make use of experimental as well as statistical (i.e., path analytic) procedures to test hypotheses derived from recent theory and data. The results of this project will yield new and important knowledge concerning the manner in which people acquire, retain, and utilize social information. The research has important implications for various models of mental health that draw heavily on the social perception/cognition literature.