Preceding essays have documented the dramatic growth of transnational relations between Canadians and Americans and have emphasized the development of new issue areas—private, local, regional, and national—between the two countries. As these relations expand in scope, complexity, and occasionally conflict, we would expect to see a corresponding growth in Canadian-American institutions to provide mechanisms for policy coordination, bargaining, and conflict resolution. The increase in formal governmental institutions between Ottawa and Washington has indeed been notable, but we must not conclude that these institutions constitute the core of the intergovernmental relationship. The informal and formal communications between federal government bureaucracies and between officials of the states and provinces are no less important; hence, the essay will focus not only on the bilateral institutions but also on the phenomenon that Nye and Keohane have called transgovernmental relations, that is, the non institutionalized relationships between subunits of governments and the activities they undertake that remain reasonably immune from central control (see their preceding essay in this volume).