Denis Hayes rose to prominence in 1970 as the national coordinator for the first Earth Day. With an estimated 20 million participants, it remains the largest planned event in the nation’s history. In 2009, the story of Earth Day was told in the film “Earth Days,” which closed that year's Sundance Film Festival. He later founded Earth Day Network and expanded the event to more than 180 nations. Earth Day is now the world’s most widely observed secular holiday, and Denis remains its honorary chair.
During the Carter Administration, Denis was appointed head of the President’s signature “Solar Energy Research Institute” (now the National Renewable Energy Laboratory). After a successful tenure of three years, he resigned in protest when the Reagan administration slashed the Institute’s budget by three-fourths.
Denis has been a visiting scholar at the Woodrow Wilson Center, a senior fellow at the Worldwatch Institute, an adjunct professor of engineering at Stanford University, and a Silicon Valley lawyer. He has served on dozens of governing boards, including those of Stanford University, the World Resources Institute, the Federation of American Scientists, The Energy Foundation, Children Now, the National Programming Council for Public Television, the American Solar Energy Society, Greenpeace, CERES, and the Environmental Grantmakers Association. He gives many speeches every year at forums around the country. With his wife Gail Boyer Hayes, Denis co-authored Cowed: The Hidden Impact of 93 Million Cows on America's Health, Economy, Politics, Culture, and Environment (W.W. Norton, 2015).
Since 1992, Denis has been president of the Bullitt Foundation in Seattle. His mission is to make the Pacific Northwest a global model for sustainable development. To "walk its talk,” the foundation is currently constructing what will be the world’s greenest office building.
Denis has received the national Jefferson Medal for Outstanding Public Service as well as the highest awards bestowed by the Sierra Club, The Humane Society of the United States, the National Wildlife Federation, the Natural Resources Council of America, the Global Environmental Facility of the World Bank, the Interfaith Center on Corporate Responsibility, the Commonwealth Club, and the American Solar Energy Society. Time Magazine named him as a “Hero of the Planet.” He has been profiled as "Newsmaker of the week" by ABC News and as "Today’s Person in the News" by The New York Times. For perhaps his least-known award, the tiny island nation of Palau put his picture on a postage stamp.