Objective: Biopsychosocial-cultural formulation is an essential skill for medical students to become familiar with during their psychiatry clerkship. The authors describe their use of mechanistic case diagramming to demonstrate to students, in a single teaching session, how to construct a biopsychosocial-cultural formulation, and they present results of an evaluation of the session's effect on students. Methods: Questionnaires exploring students' views and understanding of biopsychosocial-cultural formulation were administered to 16 students before and after teaching sessions. Results: Significant increases were observed after the teaching sessions in self-reported understanding of and comfort with presenting a biopsychosocial-cultural formulation and in ratings of the importance of showing linkages between biological, psychological, and sociocultural factors. Conclusions: The technique of mechanistic case diagramming may be a useful approach for teaching biopsychosocial-cultural formulation.