Argues that the "social union" represents a fundamental change in the evolution of social policy in Canada as governments work together to address major problems in a spirit of collaboration and partnership and in a coordinated way across governments and policy sectors. This paper explores a number of broad governance issues related to the social union, such as implementing outcome measurement as a way of increasing governments' accountability for results and mobilizing collective action around social priorities, creating institutions to handle new functions in the social union, and engaging citizens in the construction of the social union. The most significant conclusion of the paper is that we need mechanisms to manage interdependence within the federation. Without them, Canada is missing key piece of governance. First Ministers should address this problem by expanding the scope of the current social union discussions, building more structures for these discussions, and opening them up to citizens.