The term family-based therapy for adolescent drug abuse actually describes a collection of intervention models, some of which have been in development and testing since the late 1970s. Although each model regards the family as a primary intervention unit, models vary in how extrafamilial influences or systems are addressed. The review begins by highlighting key theoretical and clinical components of differentfamily-basedtreatmentsforadolescentdrug and behavioral problems. Then, we outline the knowns and unknowns about how, for whom, and under what conditions family-based therapy for adolescent drug abuse is effective. This interpretation is based on the findings of existing controlled trials and process studies.