This article provides an overview of adult learning principles and reviews their applicability and effectiveness in enhancing learner acquisition of psychosocial competencies. It presents a brief critique of traditional models of teaching medical students, reviews general principles of adult learning, describes the method of problem-based learning (PBL), summarizes data about outcomes of PBL, and suggests mechanisms through which PBL may enhance psychosocial learning. The author emphasizes the roles of small group interaction, exposure to diverse viewpoints, integrated presentation of psychosocial issues in cases, learning to adapt to uncertainty, and similarities with the process of psychotherapy as possible mediators for enhanced psychosocial learning through PBL.