Data from 399 adolescents, who participated in one of four randomly controlled trials of the Adolescent Community Reinforcement Approach (A-CRA) intervention, were used to examine the extent to which exposure to A-CRA procedures mediated the relationship between treatment retention and outcomes. Although zero-order correlations indicated that retention in treatment was a significant predictor of alcohol and other drug (AOD) use (r = -0.18, p < .001), this relationship was reduced to nonsignificance (p = .39) when exposure to A-CRA procedures was included in the model. Overall, the final model evidenced a very good fit (root mean square error of approximation = .00; comparative fit index = 1.00) and explained 29% and 43% of the variance in adolescents' posttreatment AOD use and AOD-related problems, respectively. In addition, Chi-Squared Automatic Interaction Detection analysis was used to derive a target level of A-CRA exposure, which was found to be significantly related to being in recovery at follow-up. The current findings are useful, as little research to date has identified significant mediators of the relationship between retention and treatment outcomes or identified target thresholds of treatment exposure.