Given the public health importance of depression, the identification of prevention programs with long-term effects on reducing the rate of depression is of critical importance, as is the examination of factors that may moderate the magnitude of such prevention effects. This study examines the impact of the Family Check-Up, delivered in public secondary schools beginning in sixth grade, on the development of major depression in adulthood (aged 28-30). The multilevel intervention program included (a) a universal classroom-based intervention focused on problem solving and peer relationship skills, (b) the Family Check-Up (selected), a brief assessment-based intervention designed to motivate parents to improve aspects of family functioning when warranted, and (c) family management treatment (indicated), focused on improving parenting skills. Demographic (gender and ethnicity) and baseline risk factors (family conflict, academic problems, antisocial behavior, and peer deviance) were examined as possible moderators in logistic regression analyses. Intervention effects on depression were moderated by baseline family conflict and academic performance, with stronger intervention effects for youth with low grade point averages and from low-conflict families at baseline. Such findings extend the emerging literature on prevention programs with long-term effects on depression, and highlight directions for future research to enhance such effects.