Depression is a prevalent, chronic, and impairing condition that is often undetected and becomes more difficult to treat as chronicity increases. There is an increasing need to conduct large-scale depression prevention studies in adolescents. This study evaluates a cognitive-behavioral prevention (CBP) program to determine its effectiveness in preventing depressive disorders in at-risk adolescents. The study also will ascertain the costs this intervention to inform attempts at future dissemination of the program in "real world" settings.