Background: Despite overwhelming evidence of the health benefits of physical activity, most American youth are not meeting the 60 minutes per day recommendation for moderate- to vigorous-intensity physical activity (MVPA). Policy changes have the potential to bring about substantial increases in physical activity in youth, within school and community settings. Purpose: The purpose of this study was to quantify the increase in energy expenditure for school-based policies and built environment changes. Methods: Scientific literature reviews were consulted, and more than 300 published studies (1995-2011) in English were identified based on titles and abstracts. After an initial screening, 85 articles were included. Study quality was assessed, and the impact of various strategies for increasing physical activity in youth was estimated from objective measurements/direct observation. Results: Within school settings, the average minutes of MVPA gained per school day for studies in each intervention category were as follows: mandatory physical education (23 minutes); classroom activity breaks (19 minutes); afterschool activity programs (10 minutes); standardized physical education curricula (6 minutes more than traditional physical education); modified playgrounds (6 minutes); and modified recess (5 minutes more than traditional recess). Within community settings, significant MVPA was associated with active commuting (16 minutes) and park renovations (12 minutes), but proximity to parks had a small effect (1 minute). No conclusions could be drawn regarding joint-use agreements, because of a lack of studies quantifying their impact on energy expenditure. Conclusions: Of the various policies and built environment changes examined, the largest effects were seen with mandatory physical education, classroom activity breaks, and active commuting to school. Policymakers can use this information along with estimates of the cost, feasibility, and population reach, to identify the best options for increasing physical activity in youth. © 2013 American Journal of Preventive Medicine.