This study examined the efficacy of Collaborative & Proactive Solutions (CPS) in treating oppositional defiant disorder (ODD) in youth by comparing this novel treatment to Parent Management Training (PMT), a well-established treatment, and a waitlist control (WLC) group. One hundred thirty-four youth (ages 7-14, 61.9% male, 83.6% White) who fulfilled Diagnostic and Statistical Manual of Mental Disorders (4th ed.) criteria for ODD were randomized to CPS, PMT, or WLC groups. ODD was assessed with semistructured diagnostic interviews, clinical global severity and improvement ratings, and parent report measures. Assessments were completed pretreatment, posttreatment, and at 6 months following treatment. Responder and remitter analyses were undertaken using intent-to-treat mixed-models analyses. Chronological age, gender, and socioeconomic status as well as the presence of comorbid attention deficit/hyperactivity and anxiety disorders were examined as predictors of treatment outcome. Both treatment conditions were superior to the WLC condition but did not differ from one another in either our responder or remitter analyses. Approximately 50% of youth in both active treatments were diagnosis free and were judged to be much or very much improved at posttreatment, compared to 0% in the waitlist condition. Younger age and presence of an anxiety disorder predicted better treatment outcomes for both PMT and CPS. Treatment gains were maintained at 6-month follow-up. CPS proved to be equivalent to PMT and can be considered an evidence-based, alternative treatment for youth with ODD and their families.