Preliminary evidence suggests that mental health consumers can successfully serve as peer companions, case management aides, case managers, job coaches, and drop-in center staff. However, few empirical investigations have addressed the use of consumers to train mental health professionals. This project employed a randomized design to test the effects of using consumers as trainers for mental health service providers. Fifty-seven state mental health professionals participated in a two-day training designed to acquaint trainees with the attitudes and knowledge necessary for delivering assertive case management services. Participants were randomly assigned to one of two conditions: one in which they received the second day of training from a consumer and the other involving training by a nonconsumer. Analyses revealed that post-training attitudes were significantly more positive for those participants trained by the consumer. Subjective evaluations also reflected positive reactions to the use of consumers as trainers. Implications for further use of mental health consumers as trainers are explored.