Active play takes place during a child's free time (Brockman et al., 2011), and has been shown to enhance children's physical, social, emotional and cognitive development (Burdette & Whitaker, 2005). Despite the noted benefits, there has been a significant decline in children's active play over the past 50 years (Gray, 2011). Therefore, it is important to further our understanding of children's active play to help facilitate physical activity participation. The purpose of this study was to conduct a literature review on children's active play. More specifically, we sought to answer three research questions: 1) How active play is defined; 2) How active play is measured; and 3) What are the facilitators and barriers to active play. Searches were conducted using computerized databases (e.g. SPORTDiscus, PsychInfo) between January and April of 2014. A total of 27 studies spanning from 2006-2014 were analyzed. Several definitions of active play were proposed across studies, suggesting the need for an operational definition. Common measures of active play included accelerometers and questionnaires. Facilitators to active play included gender, play location (backyard vs. neighborhood), type of play and playmate choice. Environments that were autonomy-supportive, unstructured, natural and close to home were positively associated with active play, while high levels of sedentary time were associated with decreased levels of active play. Barriers to children's active play included parental constraints, safety concerns, weather conditions and technology. Recommendations for future research and strategies to promote active play are provided.