This chapter reviews theories, arguments and empirical evidence on how territorial forces shape environmental policies. While common approaches, including comparative environmental federalism, economic federalism, and policy diffusion and convergence, stress that territory shapes environmental policies, they fail to explain how. An actor-centred, and hence political, take on common findings highlights mechanisms by which territorial politics matter. The second part of this chapter does so by distinguishing between three main categories of actors: political parties; interest groups; and federal jurisdictions. Under each heading, findings in the literature are discussed before exploring how those are found to play out in two well-researched policy areas: climate change and resource management. When it comes to climate change action, territorial politics tends to be shaped by party politics and, to a lesser extent today, interest group politics. By contrast, interest group politics and intergovernmental disputes govern the territorial politics of resource management.