The United States is currently experiencing an epidemic of children who are overweight or obese. Recently, research on child obesity has begun to examine the relationship between neighborhood environments and the health behaviors of youths. The current study used growth curve analysis based on multilevel modeling to examine the relationship between parents' perceptions of neighborhood safety and children's body mass index (BMI). Parents' perceptions of neighborhood safety had a significant association with children's BMI, and this relationship was fully mediated by television viewing. The results of this study suggest that when parents perceive their neighborhood to be unsafe, they will restrict their children's outdoor activities and increase the likelihood of sedentary indoor activity. Policies aimed at reducing overweight and obesity in children should take into account the neighborhood contexts in which children live.