This chapter examines the evolution and impacts of grassroots environmental politics in California’s second largest city, San Diego, since the 1960s. Using case studies of key environmental struggles over time, it investigates how local groups—from white-gloved environmental activists in the 1960s, biodiversity advocates in the 1990s, tribal nations and trans-border coalitions for environmental justice after 2000—claimed and created meaningful places in the metropolitan landscape, how they mobilized around them, and how these efforts affected policy and politics. San Diego is an exemplary suburban metropolis to explore these developments. As a diverse, sprawling, auto-dominant metropolis on the U.S.-Mexico border in a region recognized as a global biodiversity hotspot, key trends in modern environmental history came together in this place. The metro region was also a proving ground for important innovations in urban environmental policy. Place-based politics, rooted in San Diego’s sprawling metropolitan landscapes, played key roles in these initiatives. Through primary document analysis, oral history, and participant observation, the chapter evaluates the origins, impacts, and limitations of place-based activism to achieve equitable social and environmental change.