Preschool children learn and develop through play. To understand how play environment design impacts childrens behavior, three to five year old children were studied while engaging in free play in three outdoor play environments ranging from simple and traditional to complex and environmental. Field research confirmed that play environments rich in natural materials and a variety of settings are complex and dynamic, therefore encouraging more varied creative and imaginative play in addition to high physical activity levels, whereas playgrounds lacking natural settings showed more predictable play and children bored more easily. Current research, along with the field work conducted, shows that incorporating a variety of natural and manmade materials into complex outdoor play environments benefits whole child development. Further research is needed to study how duration of outdoor play and adult interactions impact childrens behavior and relationship to nature, and how specific natural interventions may influence preschool playground design.