We conducted a study in which referred children with disruptive behavior disorders were randomly assigned either to a combination of parent management training and social problem-solving skills training—i.e., the Utrecht Coping Power Program (UCPP), given by clinically inexperienced, but specifically trained, therapists—or to care as usual (C), given by experienced clinicians. From pretreatment to 6-month follow-up, the costs per family were twice as high in the C-condition as in the UCPP-condition. From pretreatment to 6-month follow-up, the mean costs per mean standard deviation improvement were 42% lower in the UCPP-condition than in the C-condition. No influence of therapist experience on treatment effect was found. The number of switches in treatment method was lower in the UCPP-condition than in the C-condition. The number of treatments that ended without the mutual consent of therapist and family was lower in the UCPP-condition than in the C-condition. We conclude that for the treatment of children with disruptive behavior disorders in everyday clinical practice, manualized behavior therapy is preferable to care as usual.