Social psychology is the discipline that investigates thought processes, emotions, and behaviors in the interpersonal context. There are three broad topic domains: understanding oneself and other persons, interpersonal relations, and group influence. The most important method is the experiment. The value of the social psychological perspective is illustrated with regard to the following surgical research questions: How do surgeons arrive at their decisions? How do surgeons confirm their decisions? Why do decision aids (computer support, guidelines) receive so little acceptance? How should patients be informed? Which group processes play a role in the operating theatre? What are the determinants of patient outcomes? Social psychology can extend surgical research in three respects: better understanding of everyday phenomena in the clinical and surgical arena, methodologically refined and stronger patient-oriented study designs, and new perspectives for improved patient outcomes.