PURPOSE: This study examined factors related to two sources of physical activity for youth: active use of recreation sites and active transport to recreation sites. METHODS: Parents of children (n = 87) and matched pairs of parents and adolescents (n = 124 pairs) in three US cities reported on youths' active use of, proximity to, and walking/biking to 12 recreation sites and on neighborhood walkability and safety. Multivariate regression models evaluated factors associated with youths' frequent site use and active transport to sites. RESULTS: Proximity to the site was associated with frequent use of large parks and public open space. Walking/biking to the site was associated with frequent use of most sites (indoor recreation sites, small and large parks, basketball courts, walking/running tracks, school recreation sites, playgrounds, and public open space). After controlling for proximity and demographic factors, active transport to sites remained significantly associated (P < 0.05) with frequent use of four sites for children (indoor recreation, walking/running tracks, school recreation facilities, and public open space) and all but three sites for adolescents (indoor recreation, playfields/courts, and beach/lake/rivers). Adolescents' active transport to more sites was most positively related to higher perceived traffic safety and to better pedestrian infrastructure and was negatively related to crime threat. Adolescents with driver's licenses walked/biked to recreation sites less often. CONCLUSIONS: Active transport was strongly associated with the use of multiple recreation sites by children and adolescents, even when accounting for proximity and demographic factors. Adolescents living in neighborhoods with better traffic safety walked/biked to more recreation sites for physical activity. Findings support the need for built environments and transportation policies that facilitate safe, active transport to recreation sites for youth physical activity.