OBJECTIVE To assess how park characteristics and demographic factors are associated with park use. METHODS We studied a diverse sample of parks in a Southern California metropolitan area in 2006-2008 representing a variety of racial and ethnic communities of different socioeconomic strata. We surveyed 51 park directors, 4257 park users and local residents, and observed 30 parks. We explored relationships among the number of people observed, the number of park programs offered, number of organized activities observed, park size, existence of park advisory board, perceptions of safety, and population density and characteristics. RESULTS The strongest correlates of the number of people using the park were the park size and the number of organized activities observed. Neighborhood population density, neighborhood poverty levels, perceptions of park safety, and the presence of a park advisory board were not associated with park use. CONCLUSION While perceptions of low safety have been considered a barrier to park use, perceptions of high safety do not appear to facilitate park use. Having events at the park, including sports competitions and other attractions, appears to be the strongest correlate of park use and community-level physical activity.