Bruce Hamilton is a wildlife biologist and environmental activist who worked in a variety of positions as a Sierra Club staff member from 1977 to 2021, including as Field Director, Conservation Director, and Deputy Executive Director. Hamilton was born in March 1951 in Toronto, Canada. Two years later, his family moved to Ithaca, New York, where his father taught forestry at Cornell University. In 1969 and 70, Hamilton attended SUNY Old Westbury's experimental college, and through the Scripps Institute of Oceanography he traveled with the Aries Expedition to the South Pacific. Upon returning to the United States, Hamilton earned his undergraduate degree in 1973 in Wildlife Biology and Natural Resources Administration from Colorado State University. In Colorado, Hamilton met Joan Nice, whom he married upon moving to Lander, Wyoming, where they ran High Country News for several years. They have two children. In 1977, Hamilton joined the staff of the Sierra Club as its Northern Plains Regional Representative where, among other activities, he worked to stop or mitigate fossil-fuel energy projects and protect public lands as wilderness. In December 1983, Hamilton and his family moved to the Bay Area near the Sierra Club's national headquarters to become the Club's first Director of Conservation Field Services. Over several decades, Hamilton served various roles for the Sierra Club, including as Director of Conservation and Communications; as Deputy Executive Director to two Sierra Club Executive Directors, Carl Pope and Michael Brune; and as the Director of National Policy until his retirement in May 2021. In this oral history, Hamilton discusses all of the above with particular detail on his Sierra Club career, the numerous campaigns he worked in, and major transitions and tensions within the Sierra Club, including the evolution of the Club's field staff and organizing department, changes in executive leadership, the rise of climate change as a top priority issue, as well as the Club's recent reckoning over its past with regard to racial discrimination and its work towards environmental justice. Soon after recording this oral history, Hamilton received in 2021 the Sierra Club San Francisco Bay Chapter's Ed Bennett Lifetime Achievement Award, and in 2024 he received the Changemaker of the Year Award, formerly called the John Muir Award, the national Sierra Club's top honor.