Community-based interventions offer a promising solution for reducing child and adolescent unintentional injuries. By focusing on altering behavior, promoting environmental change within the community, or passing and enforcing legislation, these interventions seek to change social norms about acceptable safety behaviors. This article systematically reviews 32 studies that evaluated the impact of community-based injury prevention efforts on childhood injuries, safety behaviors, and the adoption of safety devices. Interventions targeted schools, municipalities, and cities. Most relied on an educational approach, sometimes in combination with legislation or subsidies, to reduce the cost of safety devices such as bicycle helmets. Results indicate that community-based approaches are effective at increasing some safety practices, such as bicycle helmet use and car seat use among children. The evidence is less compelling that such interventions increase child pedestrian safety, increase adolescent vehicle safety by reducing drinking and driving behaviors, or reduce rates of several categories of childhood injuries. Strong evidence supporting the effectiveness of community-based interventions is lacking, in part because few studies used randomized controlled designs or examined injury rates among children and youths as outcome measures. Nonetheless, this review identifies common elements of successful community-based approaches that should be replicated in future studies. First, the use of multiple strategies grounded in a theory of behavior change is critical. Second, to maximize success, interventions should be integrated into the community and approaches should be tailored to meet unique community needs. Third, community stakeholders should be included in the development of community-based strategies. This community involvement and ownership of the intervention increases the likelihood of modeling and peer pressure, leading to widespread adoption of a safety behavior. Finally, when possible, a randomized controlled design should be used to maximize the trustworthiness of reported findings and aid decisions about where to invest resources in community-based approaches to injury prevention.