Abstract : Peer evaluation research was reviewed from the three major perspectives of validity studies, methodology, and situational factors. Most of the research programs were conducted in the course of developing procedures for evaluating training groups (e.g., in Officer Candidate School, U.S. Military Academy, and Ranger course). Substantial concurrent and predictive validity generally was found, with correlation coefficients in the .30 to .50 range. Different evaluation methods (rating, ranking, nominations, and combinations of these techniques) did not differ substantially in either reliability or validity. Evaluation methods did, however, differ in acceptability and feasibility. Situational factors have documented or potential effect on the evaluation process that developers and users of peer evaluations should be aware of. Although many issues surrounding peer evaluations remain unresolved, evidence suggests that these issues can be resolved, and that they do not detract from the conclusion that peer evaluations are a powerful tool in discriminating complex human behavior.