Investigating children's outdoor play unites scholarship on neighborhoods, parental perceptions of safety, and children's health. Utilizing the Fragile Families and Child Well-being Study (N=3,448), we examine mothers' fear of their five-year-old children playing outdoors, testing associations with neighborhood social characteristics, city-level crime rates, maternal mental health, and social support. Living in public housing, perceptions of low neighborhood collective efficacy, and living in a Census tract with a higher proportion of Blacks and households in poverty are associated with higher odds of maternal fear, but crime rates are not a significant predictor of fear. We also demonstrate that not being depressed - but not social support or collective efficacy - buffers the influence of neighborhood poverty on maternal fears of outdoor play.