Background. Childhood obesity rates have risen markedly in the U.S. over the last 25 years. Apart from the nutritional considerations that are well-documented, child overweight is associated with low levels of physical activity (PA). Although a number of studies address the environmental barriers to adult PA, research on children is limited. The purpose of this study was to explore the barriers to outdoor play in the summertime as perceived by children themselves. Methods. In the summer of 2012, 281 children ages 6–14 years were surveyed as to things that would keep them from playing outdoors. Results. The top three factors named by boys were bad weather, fear of gangs/crime, and preferring indoor activities like video games. Girls also named bad weather most often, followed by it being too hot outdoors, and fear of gangs/crime. Conclusion. Children view unsafe neighborhoods and bad weather as the primary barriers to outdoor play. Allowing access to unused school gymnasiums may be a useful strategy for facilitating children’s PA in the summer months.