This article summarizes and synthesizes my several papers on attribution theory (Kelley, 1967, 1971, 1972). Lest the reader incorrectly conclude that these writings define attribution theory, note must be made of other statements of the theory. These include, most importantly, Fritz Heider's (1958) book, The Psychology of Interpersonal Relations, which has played a central role in the orgination and definition of attribution theory and continues to be the major source of ideas; Ned Jones and Keith Davis' (196S) systematic hypotheses about the perception of intention in their essay on "From Acts to Dispositions"; and Daryl Bern's imaginative work on the theory of self-perception (summarized in a recent paper, 1972). Deserving attention as a broad survey of the field is the recent volume edited by Jones, Kanouse, Kelley, Nisbett, Valins, and Weiner (1972), entitled Attribution: Perceiving the Causes of Behavior. Attribution theory is a theory about how people make causal explanations, about how they answer questions beginning with "why?" It deals with the information they use in making causal inferences, and with what they do with this information to answer causal questions. The theory has developed within social psychology primarily as a means of dealing with questions of social perception: If a person is aggressively competitive in his behavior, is he this kind of person, or is he reacting to situational pressures? If a person advocates a certain political position, does this reflect his true opinions, or is it to be explained