Research has demonstrated that children who participate in active play are more likely to be physically active, thereby improving long-term health outcomes. Many adult studies have also shown that neighborhood built environments can encourage or discourage routine physical activity. Limited evidence has demonstrated that children who reside in neighborhoods with a built environment that is more inviting to active play exhibit lower overweight and obesity rates as well as an overall better state of well-being. This Built Environment and Active Play (BEAP) Study aims to develop a neighborhood playability rating system in the Washington, DC (DMV) area. Similar to walkability scores, these playability scores will estimate how affable a neighborhood is to active play. The BEAP Study will attempt to provide a broad view of factors influencing the level and type of active play among children. Using a cross-sectional design, the BEAP Study will collect data using a mail questionnaire administered to the parents and/or guardians of 2000 children aged 7-12 years residing in select DMV areas in October of 2014. Questionnaire data, including information on active play, home and neighborhood characteristics, parental perceptions, and sociodemographic characteristics will be merged through a geographic information system (GIS) with objective built environment measures in the participants’ neighborhoods. An ordered logit model will be used to regress an ordinal active play outcome on built environment exposure variables while adjusting for potential confounders. Upon the construction of the final model, predictor coefficients will be used as parameters in the scoring system to develop neighborhood playability scores. The BEAP Study intends to generate a neighborhood playability index by characterizing and quantifying children’s active play using parent-reported physical activity data in children, GIS data and built environment measures in participant neighborhoods. The BEAP Study will improve our understanding of the built environment and childhood playability relationship while also contributing to the body of evidence-based built environment and physical activity research.