CONTEXT: The extant literature on the treatment of pediatric obsessive-compulsive disorder (OCD) indicates that partial response to serotonin reuptake inhibitors (SRIs) is the norm and that augmentation with short-term OCD-specific cognitive behavior therapy (CBT) may provide additional benefit. OBJECTIVE: To examine the effects of augmenting SRIs with CBT or a brief form of CBT, instructions in CBT delivered in the context of medication management. DESIGN, SETTING, AND PARTICIPANTS: A 12-week randomized controlled trial conducted at 3 academic medical centers between 2004 and 2009, involving 124 pediatric outpatients between the ages of 7 and 17 years with OCD as a primary diagnosis and a Children's Yale-Brown Obsessive Compulsive Scale score of 16 or higher despite an adequate SRI trial. INTERVENTIONS: Participants were randomly assigned to 1 of 3 treatment strategies that included 7 sessions over 12 weeks: 42 in the medication management only, 42 in the medication management plus instructions in CBT, and 42 in the medication management plus CBT; the last included 14 concurrent CBT sessions. MAIN OUTCOME MEASURES: Whether patients responded positively to treatment by improving their baseline obsessive-compulsive scale score by 30% or more and demonstrating a change in their continuous scores over 12 weeks. RESULTS: The medication management plus CBT strategy was superior to the other 2 strategies on all outcome measures. In the primary intention-to-treat analysis, 68.6% (95% CI, 53.9%-83.3%) in the plus CBT group were considered responders, which was significantly better than the 34.0% (95% CI, 18.0%-50.0%) in the plus instructions in CBT group, and 30.0% (95% CI, 14.9%-45.1%) in the medication management only group. The results were similar in pairwise comparisons with the plus CBT strategy being superior to the other 2 strategies (P < .01 for both). The plus instructions in CBT strategy was not statistically superior to medication management only (P = .72). The number needed-to-treat analysis with the plus CBT vs medication management only in order to see 1 additional patient at week 12, on average, was estimated as 3; for the plus CBT vs the plus instructions in CBT strategy, the number needed to treat was also estimated as 3; for the plus instructions in CBT vs medication management only the number needed to treat was estimated as 25. CONCLUSIONS: Among patients aged 7 to 17 years with OCD and partial response to SRI use, the addition of CBT to medication management compared with medication management alone resulted in a significantly greater response rate, whereas augmentation of medication management with the addition of instructions in CBT did not. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00074815.