Background: School-based study recruitment efforts are both time consuming and challenging. This paper highlights the recruitment strategies employed by the national, multisite Trial of Activity for Adolescent Girls (TAAG), a study designed to measure the effectiveness of an intervention to reduce the decline of physical activity levels among middle school-aged girls. TAAG provided a unique opportunity to recruit large cohorts of randomly sampled girls within 36 diverse middle schools across the United States. Methods: Key elements of the formative planning, coordination, and design of TAAG's recruitment efforts included flexibility, tailoring, and the use of incentives. Various barriers, including a natural disaster, political tension, and district regulations, were encountered throughout the recruitment process, but coordinated strategies and frequent communication between the 6 TAAG sites were helpful in tailoring the recruitment process at the 36 intervention and control schools. Results: Progressively refined recruitment strategies and specific attention to the target audience of middle school girls resulted in overall study recruitment rates of 80%, 85%, and 89%, for the baseline, posttest, and follow-up period, respectively. Discussion: The steady increase in recruitment rates over time is attributed to an emphasis on successful strategies and a willingness to modify less successful methods. Open and consistent communication, an increasingly coordinated recruitment strategy, interactive recruitment presentations, and participant incentives resulted in an effective recruitment campaign. (Contains 3 tables.)