By the early 1970s, the Bay Area was in the midst of great social and cultural change. With plans for the extension of BART into the East Bay, and suburban sprawl threatening Mount Diablo and other open spaces, Save Mount Diablo (SMD) answered a call to action. SMD was founded by Dr. Mary Bowerman and Arthur Bonwell in 1971. It became a nationally accredited land trust based in the San Francisco Bay Area comprised of biologists, conservationists, hikers, cyclists, equestrians, bird watchers, artists, and people who just loved to look at and enjoy the mountain. SMD has been preserving lands on and around Mount Diablo and educating the public to the mountain’s natural values since its founding. The organization’s focus on educational programs and protecting Mount Diablo’s connection to its sustaining Diablo Range has grown substantially over the years, due in part to new leadership and the growing severity of the climate crisis. As an organization, Save Mount Diablo is both an exceptional example of local land conservation efforts, as well as representative of national and international environmental activism that extends beyond the Bay Area. This oral history project began in 2021 as SMD approached its 50th anniversary. Most of the interviews were conducted remotely due to the global COVID-19 pandemic.