Because of the difficulty of evaluating uneven performance among group members, many researchers suggest incorporating peer evaluations in a grading system that permits an instructor to evaluate and grade individual performance more equitably within a group. In this study, the authors employ expectancy theory to assess key factors that may motivate students to participate in the peer evaluation process of group projects. Results show that students generally thought that the most attractive outcome of peer evaluation is its use in the determination of peers' grades. The second most attractive outcome is its use for reduction of conflict and uneven workload distribution among group members. The authors provide implications for instructors planning to use peer evaluation in group projects. (Contains 4 tables and 7 notes.)