Studies support the use of exercise prescriptions in adults, but few studies have evaluated their use in children. One common barrier to effective physical activity counseling is lack of resources. Outdoors Rx is a collaboration between the Appalachian Mountain Club and the Massachusetts General Hospital for Children that pairs exercise prescriptions with guided outdoor programs to increase physical activity among children. This article describes the design and implementation of Outdoors Rx at 2 community health centers serving ethnically diverse, low-income, urban families, as well as evaluates feedback from participating pediatricians regarding the utility of the program, barriers to success, and suggestions for improvement. Our results illustrate the feasibility of implementing a pediatric physical activity prescription program in community health centers serving traditionally underserved populations. Our data suggest that physical activity prescription programs are well received by both pediatricians and families and are a useful tool for facilitating physical activity counseling.