Although some entries fall under several of these categories, each is listed in the section for which it is most well-known. For example, Rock Creek Park is listed in the "Parks and Natural Area" section although it is managed by the National Park Service, which is an agency of the federal government. National Park Service Headquarters, however is listed under "Government Agencies."

We have also included a list of environmental education support organizations which are good sources of additional environmental education information, opportunities and materials.

Each entry lists the title of the organization with a brief description of its mission, followed by the programs and services it provides. Notes on reservations, wheelchair accessibility, or fees are also listed. We only list an organization's location if it is different from the mailing address, or if you are likely to visit the organization on a field study. In most cases we list the title of the person to contact, a phone number and a fax number or email address, instead of listing a name because people leave positions or get promoted and the information quickly becomes out-dated. Finally, we list the organization's mailing address, along with a fax number, email address and/or website.