CONTEXT: Most of the many clinical preventive services (CPS) recommended for adolescents by various national organizations lack good evidence of effectiveness. Improving adolescent preventive care will require focusing on those CPS for which there is such evidence and on developing better delivery strategies. The objective of the current study was to identify those CPS for adolescents that do have a strong evidence base, to update the literature review and summarize evidence gaps where research is needed, and to summarize current delivery prevalence and opportunities. EVIDENCE ACQUISITION: A summary was conducted of the recommendations for adolescents of the U.S. Preventive Services Task Force (USPSTF) and the CDC's Advisory Committee on Immunization Practices (ACIP). An update is provided of the literature review for services with an inadequate evidence base to support a recommendation. A summary was prepared of the types of evidence still needed. A literature search was also conducted for current delivery prevalence of recommended services for those aged 11-17 years, and common gaps in the evidence were identified. EVIDENCE SYNTHESIS: Although 24 CPS for adolescents have been reviewed by the USPSTF, only ten received definite recommendations and only seven of these favored delivery of the service. In addition, the ACIP recommends four immunizations for all adolescents, and two additional ones for those at high risk. There are many gaps in the evidence supporting most of the other services as well as in the information about current delivery prevalence. CONCLUSIONS: There are too many CPS recommended for adolescents with insufficient evidence of effectiveness, and there is low delivery prevalence for the few services with good evidence of effectiveness. Both more research and more attention to the practice changes that might improve delivery prevalence are needed.