Objective: To determine whether a systems intervention for primary care providers resulted in increased preventive screening and counseling of adolescent patients, compared with the usual standard of care. Methods: The intervention was conducted in 2 out-patient pediatric clinics; 2 other pediatric clinics in the same health maintenance organization served as comparison sites. The intervention was implemented in 2 phases: first, pediatric primary care providers attended a training workshop (N = 37) to increase screening and counseling of adolescents in the areas of tobacco, alcohol, drugs, sexual behavior, and safety (seat belt and helmet use). Second, screening and charting tools were integrated into the intervention clinics. Providers in the comparison sites (N = 39) continued to provide the usual standard of care to their adolescent patients. Adolescent reports were used to assess changes in provider behavior. After a well visit, 13- to 17-year olds (N = 2628) completed surveys reporting on whether their provider screened and counseled them for risky behavior. Results: Screening and counseling rates increased significantly in each of the 6 areas in the intervention sites, compared with rates of delivery using the usual standard of care. Across the 6 areas combined, the average screening rate increased from 58% to 83%; counseling rates increased from 52% to 78%. There were no significant increases in the comparison sites during the same period. The training component seems to account for most of this increase, with the tools sustaining the effects of the training. Conclusions: The study offers strong support for an intervention to increase clinicians' delivery of preventive services to a wide age range of adolescent patients.