A number of organizations in the United States stand out in terms of their divestment efforts.
Co-founded by Bill McKibben, this organization represents a planet-wide, grassroots climate change movement. 350.org is named for the safe level of Carbon Dioxide in the atmosphere, 350 parts per million. This website is an excellent resource for materials on divestment.
Better Future Project
The mission of the Better Future Project is to build a diverse and powerful grassroots movement to address climate change and its devastating effects, advancing a transition beyond coal, oil, and gas toward an economy powered by renewable energy that equitably benefits all people.
Go Fossil Free
Working closely with 350.org, Go Fossil Free is part of a growing global climate movement. From online campaigns and grassroots organizing to public actions, the organization coordinates events in over 180 countries. This is another excellent website for resources on divestment.
A partner with 350.org and the Go Fossil Free divestment campaign, Green America provides information on broad-based mutual funds that exclude fossil-fuel companies.