The aims of the Physical Activity Partnership for Girls (PG) are to: 1) build a strong community-academic partnership and assess community priorities and needs for physical activity (PA) promotion among Latino adolescent girls (age ll-14yr) in Westside San Antonio, Texas;2) design, jointly, an intervention to increase moderate to vigorous PA (MVPA) and reduce sedentary behavior among Latino adolescent girls that can be offered and sustained through Girl Scouts (GS) of Southwest Texas and incorporates low-cost, mobile, and wireless technology to promote health and connect youth to community resources;and, 3) use a group randomized trial design to pilot test the PA intervention to ascertain its feasibility and effects among Latino adolescent girls. In year 1, we propose to conduct formative assessments and develop the intervention in full partnership with two local organizations in the target area, one serving youth and one serving families, as well as other community partners via a Community Advisory Board. Data gathered from 4 parent focus groups (~50 participants), 10 in-depth interviews, 5 GS groups (~60 participants) using the photovoice assessment strategy, and 100 media survey participants will inform the development of an intervention to promote MVPA and reduce sedentary behaviors among Latino adolescent girls. In year 2, the intervention will be implemented in the Westside by GS troop leaders with guidance and support from research staff. Standardized assessments will occur at baseline, 3-months, and 6-months and PA will be assessed using accelerometers and PA recall questionnaires. We hypothesize that a significantly higher percententage of participants randomized to the PA intervention will meet the PA recommendation for MVPA (60 min/d) and sedentary behavior (<2 hr/d) compared to those randomized to the usual GS program (primary outcomes);show greater increases in social support, self-efficacy, enjoyment of PA, cardiorespiratory fitness, and less gain in weight and Body Mass Index (secondary outcomes) compared to the control group. RELEVANCE (See instructions): Hispanic adolescent girls are burdened with high levels of obesity and are less active than the general adolescent population. Creative strategies developed with community input are needed if we are to improve PA among this high-risk group.