Policies relevant to many key sociological processes are often subnational, enacted at the regional, state/provincial, and/or local levels. This applies notably in the politics of the environmental state, where public and private subnational environmental policies (SNEPs) have major consequences for managing climate change, addressing environmental injustices, regulating land uses, greening energy markets, limiting pollution, and much more. While sociologists focus more on national policies, diverse sociological contributions emphasize the importance of SNEPs and their origins, diffusion, implementation, and sources of backlash. We begin by providing a typology of SNEPs. Next, we highlight not only environmental sociology (with its particular attention to climate change and energy) but also the sociologies of social movements, politics, the economy, science, risk, and organizations, which have each offered unique perspectives. Finally, we outline an agenda for how sociologists can further elaborate a distinctive perspective that highlights inequality, valuation, diffusion, scale shifts, and venue-shopping up to national and global policy systems.