Background: School policies and practices, such as the sharing of school facilities with the surrounding community, support physical activity among students and community members, but are often underutilized. This study examined variations in shared use practices, and associations with perceived barriers. Methods: Surveys were completed by a nationally representative sample of 640 public elementary schools across the United States. Administrators reported on their school's practices related to the shared use of indoor and outdoor facilities, and perceived barriers to sharing. Multivariate logistic regression models were used to examine associations between barriers and practices. Results: Liability or legal concerns, staffing expenses, and facility operation costs were most frequently reported as barriers, while lack of adequate facilities and perceived lack of community interest were less common. Cost concerns and perceived lack of community interest were most strongly associated with lack of sharing. Conclusions: Although liability or legal concerns are common, such concerns are not necessarily associated with less sharing when other factors are taken into account. Administrators' perceptions about lack of community interest were associated with less sharing, but these perceptions may not accurately reflect the community's perspective. Active development of partnerships could increase access to school facilities.