The Natural Resources Defense Council (NRDC) on Thursday announced president Frances Beinecke will retire at the end of 2014.
After joining the council as an intern in 1973, Beinecke became the second president in the group's history in 2006.
Beinecke said that she made the news of her retirement public in order to give the council ample time to find her replacement.
"I will continue the fight to protect our environment and curb climate change, as I have for the past 40 years," she said.
Beinecke's comes amid a broader changing of the guard at the top levels of the environmental movement.
National Wildlife Federation President and CEO Larry Schweiger plans to retire in May.
Eileen Claussen, the president of the Center for Climate and Energy Solutions, is stepping down after 15 years with the group.
Claussen founded the nonprofit policy advocacy group, which is looking to name a new president in early 2014.