C&O Canal Association

California Wildlife Federation

Canada Goose Conservation Society

Canadian Arctic Resources Committee

Canadian Parks and Wilderness Society

Canadian Wildlife Federation

Canadian World Parrot Trust

Cannon River Watershed Partnership

Caribe Rainforest Preservation Trust

Caribbean Conservation Corporation

Caribou Commons Project

Carnivore Preservation Trust

Catamount Trail Association

Center for Environmental Citizenship

Center for Economic Conversion

Center for Energy Efficiency and Renewable Technology

Center For Health, Environment and Justice

Center for International Environmental Law

Center for Marine Conservation

Center for Russian Nature Conservation

Chehalis River Council

Chesapeake Bay Foundation

Citizens Committee to Complete the Refuge

Clark Fork - Pend Oreille Coalition

Climate Institute

Coalition for Vehicle Choice

Coalition to Prevent the Destruction of Canada Geese

Coastal Conservation Association

Columbia River Alliance

Columbia River United

Communities for a Better Environment

Connecticut Appalachian Trail Club

Conservation Agency

Conservation Fund

Conservation Law Foundation

Continental Divide Trail Alliance

Continental Divide Trail Society

Coral Reef Alliance

Cosanti Foundation

CREST