The YouthNet drug prevention program operated as a partnership involving neighborhood community centers and the school district. It was assumed that youth involvement in program activities would improve functioning in several areas: drug use, attitudes, and knowledge; peer relations; self-attributes such as self-esteem and civic and social responsibility; and school behavior. The evaluation employed a longitudinal panel design with data collected at two points in time, an initial interview and a followup interview 6 to 8 weeks later. Data obtained from 100 subjects indicated that the YouthNet program improved the functioning of participants and contributed to the prevention of drug abuse. Specifically, participation in YouthNet acted to insulate youth to some extent from environmental elements that encourage drug use. In addition, YouthNet had an impact on participants by fostering antidrug use attitudes, particularly with respect to legal drugs. The program also facilitated participant friendships with conventional others and tended to discourage thoughts about dropping out of school. While YouthNet showed considerable impact as a drug prevention program, the program did not produce expected changes in self-attribute dimensions, especially anger control, civic responsibility, respect for property, and self-esteem. 4 tables