Environmental degradation, childhood obesity, and aggression of youth are societal problems that appear unconnected. However, their cause (and possible solution) may be linked to a common experience--the amount and quality of time spent in the natural world. Environment based education, significant life experience research, and studies involving urban youth and green spaces have shown that children's experiences in the natural world have a positive effect on their attitudes, behaviors, and environmental awareness. Nature center based preschools are one approach for connecting children and nature, but little is known about the quality and consistency of their practices. This study explored program practices at preschools located at or operated by American nature centers. The purpose of this qualitative multiple case study was to describe how these preschools integrate child development and environmental goals in teaching young children. Data collection included semi-structured interviews with eight nature preschool directors, observations of their classes, and review of their documents. Data were analyzed within case and across cases to better understand how the preschool directors create and implement curriculum and to find similarities and differences among the programs. A major finding of this study suggests that the combination of early childhood education and environmental education is more powerful together than each by itself. Nature preschool goals address both the developmental needs of young children and their biophilic tendency to focus on the natural world. High quality practices for nature preschools emerged, suggesting that a nature-focused curriculum can include both developmentally appropriate practices and environmental literacy and learning, but staff education and training is crucial for providing an excellent program. No professional standards exist today for nature preschools. Recommendations include developing quality standards for nature preschools and establishing an association or network for early childhood environmental educators. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]