The thesis develops a model of the "catalytic" state characterized by a capacity for effective industrial policy formation and effective implementation of selected policies resulting in successful long run processes of economic transformation. Over the past two decades analysts have increasingly turned to state capacity as a central variable for the explanation of economic performance. The model of the catalytic state emerges from debates on industrial policy and the developmental state. The focus is on economic policy priorities, state organizational arrangements and institutional links with non-state economic actors as central features of state capacity. The research applied the catalytic state model to Ontario's agricultural sector by asking whether and in what forms Ontario's agricultural policy could be considered catalytic over the period between 1791 and 2001. The research demonstrates that the state in the nineteenth century played a limited catalytic role in the agricultural sector but did provide some important infrastructure and the beginnings of programs encouraging human capital formation. Since the late nineteenth century the state has played a strong catalytic role, pursuing a consistent productivist agenda employing a variety of policy instruments including support to agricultural research, education, extension, market management, investment and income distribution programs. The thesis concludes that the state in Ontario has been catalytic with respect to long run transformation of the agricultural sector and has retained this capacity even over the past twenty years as the policy paradigm has shifted from Keynesianism to neoliberalism. This evidence is interpreted as supporting the argument that state capacity is an important contributor to processes of successful long run economic transformation.