It is Professor Heise's premise that the psychology of affect theoretically governs common social actions, such as those of a patient toward a doctor or a mother toward a child. Human behaviour, he argues, normally promotes the maintenance of a steady emotional state. Should events produce undue strain, the individual attempts to anticipate subsequent developments, formulate a course of action and create new events designed to confirm his established sentiments. This book lays the foundation for this approach to interpreting events: it offers a mathematical model grounded in empirical procedures for analysing what happens in social relationships. Topics covered in the book include how situations are defined and events constructed, past research on processes of impression formation, the mathematical derivation for predicting behaviour and the application of this approach to the study of roles. Throughout the book, the theory is shown to be relevant not only for the construction of social action, but also for the reconstruction of events and, in particular, for the identification of social deviants.