Background: Most adolescents do not meet national recommendations for nutrition and physical activity. However, no studies of physical activity and nutrition interventions for adolescents conducted in health care settings have been published. The present study was an initial evaluation of the PACE+ (Patient-centered Assessment and Counseling for Exercise plus Nutrition) program, delivered in primary care settings. Participants: Adolescents aged 11 to 18 years (N = 117) were recruited from 4 pediatric and adolescent medicine outpatient clinics. Participants' mean (SD) age was 14.1 (2.0) years, 37% were girls, and 43% were ethnic minorities. Intervention: Behavioral targets were moderate physical activity, vigorous physical activity, fat intake, and fruit and vegetable intake. All patients completed a computerized assessment, created tailored action plans to change behavior, and discussed the plans with their health care provider. Patients were then randomly assigned to receive no further contact or 1 of 3 extended interventions: mail only, infrequent telephone and mail, or frequent telephone and mail. Measures: Brief, validated, self-report measures of target behaviors were collected at baseline and 4 months later. Results: All outcomes except vigorous physical activity improved over time, but adolescents who received the extended interventions did not have better 4-month outcomes than those who received only the computer and provider counseling components. Adolescents who targeted a behavior tended to improve more than those who did not target the behavior, except for those who targeted vigorous physical activity. Conclusions: A primary care-based interactive health communication intervention to improve physical activity and dietary behaviors among adolescents is feasible. Controlled experimental research is needed to determine whether this intervention is efficacious in changing behaviors in the short- and long-term.