Intergovernmental relations in Latin America present a varied sample of both institutional determinants and actual dynamics. Constitutional structures regulate whether countries have a federal or a unitary system of territorial distribution of power and stipulate the territorial levels of government. Thus, constitutions structure the number of vertical and horizontal intergovernmental relations. Actual dynamics, however, depend on policy prerogatives that establish subnational authority vis-à-vis the national administration. These prerogatives, usually understood in terms of power, responsibilities, and resources, shape the territorial balance of power within a country. Power, responsibilities, and resources can be combined to apprehend the degree of authority in the hands of regional governments. Such authority is analytically organized into two dimensions: the regional power of self-rule and the power to share rule with national decision makers. This distinction helps to explain that the trend toward increasing regional authority is mostly a product of decentralization and devolution politics that have enhanced self-rule, rather than reforms that advance the shared rule dimension. Nevertheless, neither constitutional structures nor new regional policy prerogatives are the only determinants of the dynamics of intergovernmental relations. Informal institutions, such as subnational coalitions and local political clientelism, are particularly relevant to understanding the actual balance of power between national and subnational governments and among subnational arenas.