Physical activity levels begin to decline in childhood and continue falling throughout adolescence, with girls being at greatest risk for inactivity. Schools are ideal settings for helping girls develop and maintain a physically active lifestyle. This paper describes the design and implementation of "Lifestyle Education for Activity Program", or LEAP. LEAP used a health team approach with participatory strategies to provide training and support, instructional capacity building and opportunities to adapt school instructional program and environmental supports to local needs. The social-ecological model, based on social cognitive theory, served as the organizing framework for the LEAP intervention and elements of the coordinated school health program model as intervention channels. For the 12 intervention schools, LEAP staff documented 191 visits and interactions with 850 individuals over the 2-year period. Teachers reported successful implementation of most components of the intervention and demonstrated optimism for sustainability. These results indicate that a facilitative approach to intervention implementation can be used successfully to engage school personnel, and to change instructional programs and school environments to increase the physical activity level of high school girls. (Contains 6 tables and 1 figure.)