This article looks anew at the important role of physically active, outdoor play in children's social and cognitive development and the role of adults in supporting active, child-directed outdoor play. The authors describe the concept of play ecologies to highlight how children experience their environment as enlivened by their interactive inquiry. Using two episodes of physically active play, the authors discuss the purpose and sequence of the play in the context of the children's peer culture. They make policy recommendations to help teachers, parents, and organizations increase and enhance physically active play among young children.