The presentation summarized some of the approaches taken in the SYEFEST (Schoolyard Ecology for Elementary School Teachers) program for helping teachers use their schoolyards for inquirybased ecology instruction. Leadership teams including a practicing ecologist and an experienced teacher have worked with local teachers at 20 sites in North and South America to: 1) develop teachers' inquiry skills and understanding of ecology, 2) help teachers reflect on and expand their approaches to environmental education, 3) guide teachers in developing units for their own use, and 4) support teachers as they being teaching outdoors. Through intensive summer institutes held on the teachers' schoolyards and sessions during the school year, SYEFEST has achieved several important outcomes. Teachers are more comfortable and excited about teaching outdoors, they are familiar with their schoolyard's potential for teaching, they go outside much more frequently, and they use more inquiry-based techniques as a result of their SYEFEST experience.