Young children's outdoor play serves important and diverse purposes, including physical exercise and opportunities for growth in all developmental areas. Unfortunately, the amount of time that children spend engaged in unstructured, child-directed outdoor play has diminished significantly in the past generation. In this article, the authors describe some of the reasons for this decline and outline the research-supported benefits of outdoor play in general, as well as benefits of play in natural outdoor environments in particular. Suggestions for making the most of outdoor play will benefit children around the world.