This study examined client and program factors predicting initiation and engagement for 2,191 adolescents at 28 outpatient substance abuse treatment sites implementing evidence-based treatments. Using Washington Circle criteria for treatment initiation and engagement, 76% of the sample initiated, with 59% engaging in treatment. Analyses used a 2-stage Heckman probit regression, accounting for within-site clustering, to identify factors predictive of initiation and engagement. Adolescents treated in a pay-for-performance (P4P) group were more likely to initiate, whereas adolescents in the race/ethnicity category labeled other (Native American, Asian, Pacific Islander, Native Alaskan, Native Hawaiian, mixed race/ethnicity), or who reported high truancy, were less likely to initiate. Race/ethnicity groups other than Latinos were equally likely to engage. Among White adolescents, each additional day from first treatment to next treatment reduced likelihood of engagement. Although relatively high initiation and engagement rates were achieved, the results suggest that attention to program and client factors may further improve compliance with these performance indicators. (C) 2012 Elsevier Inc. All rights reserved.