Guidelines for the Preparation and Professional Development of Environmental Educators is a set of recommendations about the basic knowledge and abilities educators need to provide high-quality environmental education. The guidelines are designed to apply: (1) Within the context of pre-service teacher education programs and environmental education courses offered to students with varied backgrounds such as environmental studies, geography, liberal studies, or natural resources; (2) to the professional development of educators who will work in both formal and nonformal educational settings, offering programs at the pre-kindergarten through 12th grade levels; and (3) to full-time environmental educators as well as for those for whom environmental education is just one of their responsibilities. This document presents an ambitious overview of the abilities and knowledge of a well-prepared environmental educator. The guidelines provide a mechanism for gauging the quality of pre-service and in-service preparation programs and the abilities of environmental educators. Instead of offering fixed rules, these guidelines suggest a broad vision--a goal to work toward and a guide for professional and programmatic development. The guidelines are grounded in a common understanding of effective environmental education. For many environmental educators, that understanding is rooted in two founding documents of the field: the Belgrade Charter (UNESCO-UNEP, 1976) and the Tbilisi Declaration (UNESCO, 1978). This guide is organized around six themes. Each theme describes a skill area that must be included in the training of an environmental educator, and a sample format for the "Guidelines" is provided. Each theme is accompanied by references at the end, and appended are: The Executive Summary, Excellence in Environmental Education, and Guidelines for Learning (Pre K-12).