This document describes the Mentors, Peer Groups, and Incentives (MPI) demonstration project, a model for helping early adolescent underclass males to improve academic performance and reduce the probability of premature fatherhood. A first section discusses the working definition of the underclass as a group where dysfunctional behaviors are common; reasons for underclass growth, including a growing division of men from jobs and families; how higher academic achievement among youth and less teenage pregnancy can reduce the size of the underclass; and reasons for targeting young males. The second section reviews a few concepts in the social psychology of behavioral change to provide a conceptual framework for mentor roles. The third section describes the model, provides examples of mentor activities, and shows how mentors use peer groups and incentives as tools. Full-time mentors would serve proteges as affiliates and intimate older friends, life skills teachers, administrators of behavioral change, and academic advocates. Peer groups are an ideal tool for youth who are bound together by a common experience of rejection by the larger community and whose cultural tradition values group over individual achievement. The model would use peer groups for peer tutoring and cooperative learning. (JB)