In Canada, three distinct models of federalism govern different social programmes: classical federalism, with programmes run exclusively by one level of government; shared costs federalism, with the federal government financially supporting provincial programmes; and joint-decision federalism, where formal approval by both levels of government is mandatory before any action can take place. Each of these models creates different decision rules, altering the mix of governments and ideologies at the bargaining table, redistributing power among those who have a seat at the table, and requiring different levels of consensus for action. The result has been three separate kinds of interactions between institutions and policy during the postwar era of welfare state expansion.