Evaluated 55 families of chronically offending delinquents who were randomly assigned to parent training treatment (PTT) or to service traditionally provided by the juvenile court and the community (control condition). Offense rates, institution time for the youths, and prevalence rates for police contact were compared for the 2 groups. Results indicate that the PTT families exerted quick and effective control over their sons’ official delinquency rates. Relative to the controls, PTT families were able to establish control with significantly less reliance on incarceration. Thus, results support the viability of a PTT strategy when working with chronic adolescent delinquents. Although PTT was effective for intervention with families of delinquents, clinical work with these families was extraordinarily difficult.