This article describes an interactive computer program that presents clinical vignettes to students who then determine the proper codes according to the Diagnostic and Statistical Manual of Mental Disorders (3rd ed. [DSM–III] and 3rd ed., rev. [DSM–III–R]; American Psychiatric Association, 1980 and 1987, respectively). Seventy-eight abnormal psychology students used the tutorial and a library exercise in a counterbalanced design. Computer tutorial students had significantly greater knowledge of the DSM–III and specific diagnoses. In addition, students enthusiastically recommended the tutorial for future classes. This tutorial is appropriate for undergraduate and graduate classes. © 1990, SAGE Publications. All rights reserved.