Ed McCrea, former executive director of North American Association for Environmental Education (NAEE), calls the development of the environmental education guidelines the single most important event that has occurred in the field of environmental education in the last decade. For the first time in its history, environmental education has a set of tools that promotes unity, a common language, and the professionalization of the field. These guidelines, which are described in this document, grew from NAAEE's desire to ensure that environmental education was a part of the national standards movement. Most of all, the guidelines offer a way to ensure that environmental education materials, programs, and practitioners are of the highest possible quality.