FSG Inc., also known as FSG Social Impact Advisors, is a non-profit which provides charitable consulting services to corporations, schools, community organizations, government agencies, and private charitable foundations. The organization was founded in 2000 by Michael Porter and Mark Kramer, two Harvard Business School professors. FSG has 144 employees in six offices across the US, Europe, and India. 
FSG is funded by and gives consulting services to numerous major left-of-center nonprofits.
FSG offers consulting services in five areas: economic development, education and youth, global development, global health, and U.S. health.  The organization’s strategy focuses on making social change in targeted areas and utilizing data-driven evaluations to find best practices. Its highest-profile projects include running projects for General Mills, the Bill and Melinda Gates Foundation, and the United Nations. 
The Wallace Foundation, a left-of-center private foundation which supports underperforming schools, hired FSG to create “The School Turnaround Guide” to serve as a blueprint for targeted failing schools. 
The William and Flora Hewlett Foundation, one of the largest nonprofits in America and one which gives to numerous left-of-center causes, has paid FSG $2,720,000 for its consulting services since 2009.  Wallace paid FSG $450,000 for “a study of evaluation practices in philanthropy” in 2006.  In 2019, Wallace gave FSG $100,000 for “research on the use of data in collective impact initiatives.”  FSG also provides consulting service to Hewlett-Packard, from which the Hewlett Family made its fortune.
FSG has received funding from at least 27 nonprofits, many of which are long-time supporters of left-of-center causes.
The Carnegie Corporation, which has donated to numerous left-of-center groups since Vartan Gregorian became president in 1997, is a major supporter of FSG. The Corporation donated $150,000 in 2009, $1,000,000 in 2017, $200,000 in 2018, and $750,000 in 2019. 
The Houston Endowment, a non-profit that donates to many immigration liberalization and environmentalist efforts, is a significant funder of FSG. The Endowment gave $862,400 in 2016 and $488,000 in 2017.  FSG also provides consulting services to the Endowment. 
The Rockefeller Foundation, a major funder of liberal advocacy efforts, has become a major supporter of FSG in the last few years. In 2017, the Foundation donated $1,548,273 in 2017, $530,000 in 2017, and $300,000 in 2018.  FSG also provides consulting services to the Foundation. 
The Ford Foundation, Arcus Foundation, Omidyar Network Fund, and California Endowment are all supporters of FSG which have given undisclosed grants.  All four organizations also receive consulting services from FSG.  Its work with the California Endowment on the Building Healthy Communities Initiative project is among FSG’s most prominent projects.