This systematic review evaluates the implementation of treatment integrity procedures in outcome studies of youth interventions targeting behavioral problems. The Implementation of Treatment Integrity Procedures Scale (ITIPS), developed by Perepletchikova, Treat, and Kazdin (2007), was adapted (ITIPS-A) and used to evaluate 32 outcome studies of evidence-based interventions for youths with externalizing behavioral problems. Integrity measures were found to be still rare in these studies. Of the studies that took integrity into account, 80% approached adequacy in implementing procedures for treatment integrity. The ITIPS-A is recommended as an instrument to guide development of integrity instruments and the implementation of treatment integrity procedures in youth care.