"There have been few studies of Canadian minority governments despite the fact that between 1957 and 2008, 9 of the 18 general federal elections produced minority governments. How such governments manage to remain in power (viability) and gain support for their legislative proposals (effectiveness) has not been investigated thoroughly. Three theoretical perspectives (the rational choice tradition, new institutionalism, and the party politics and party systems approach) are used to examine the dynamics at play. Data for four minority governments (Diefenbaker 1957-58, Pearson 1963-65, Clark 1979-80, and Harper 2006-08) have been gathered from archival records, debates and votes in the House of Commons, autobiographies, third party accounts and earlier studies on minority governments. Viability and effectiveness would appear to depend on (1) bargaining power (interparty dynamics and intra-party cohesion) and (2) agenda control (House business, confidence tests and other institutional features). The study also stresses the importance of government concessions, and the capacity and skill of parliamentary actors in using the institutional and party system levers."