George Hamilton has headed the Institute for Sustainable Communities (ISC) since the nonprofit organization was created in 1991. Since then, ISC has developed and carried out 75 projects strengthening communities in 22 countries.

From 1989 to 1991, Hamilton was planning director for the State of Vermont, and chief policy advisor to Governor Madeleine M. Kunin. Hamilton was co-chair of a special commission appointed by New England Governors and Eastern Canadian premiers that organized the first international conference on sustainable development in North America (1989). He also served as chair of Governor’s Development Cabinet. From 1985 to 1989, he was a policy analyst in the Vermont Governor's office, specializing in energy, environment and telecommunications issues. From 1982 to 1985, he was executive director of the Vermont Public Interest Research Group — the state's largest citizen advocacy organization. Prior to that, Hamilton was a community organizer and an energy efficiency auditor for a low income weatherization program.

Drawing on his experience as a wilderness backpacking outfitter and guide in Alaska’s Brooks Range, Hamilton was a research assistant to the US Secretary of the Interior on the Alaska Lands Act of 1979. Hamilton has been a member of a variety of boards, commissions, and delegations designed to advance sustainable development, citizen participation, community development and/or environmental protection. He is currently on the Board of the Vermont-Karelia Rule of Law Project, the Alexander and Margaret Stewart Trust, and InterAction, a coalition of U.S.-based international nongovernmental organizations focused on the world’s poor and most vulnerable people.. Hamilton holds a BS degree in Environmental Studies and Geology from St. Lawrence University.