Purpose: To investigate factors of low-income neighborhoods and households on physical activity with a sample of adolescents from low-income neighborhoods. Methods: Middle-school-aged youth (n = 74) from a low-income neighborhood completed self-report surveys. Measures include vigorous exercise frequency, neighborhood hazards, after-school time demands, availability of facilities, quality of facilities, and perceived safety. Hierarchical multiple linear regression and Pearson product moment correlations were conducted to test hypotheses that more frequent physical activity would be associated with more available locations, better quality facilities, fewer time demands, more after-school programs, more perceived safety, and more hazards. Results: Results indicate that more physical activity was associated with more hours spent in after-school programs (r =.50, p <.001) and perception of higher quality of local facilities (r = .28, p <.05). Perception of safe adults at local facilities accounted for more variance than perception of neighborhood hazards in the association with physical activity even after accounting for gender, age, and socioeconomic status. Conclusions: Future health promotion programs should consider factors of after-school programs such as quality, cost, and presence of safe adults when attempting to increase and maintain youth physical activity in lower income areas. (c) 2005 Society for Adolescent Medicine. All rights reserved.