This dissertation analyzes environmental policy trends in frontier oil developments in two major Canadian oil dependent provinces: Alberta's tar sands and Newfoundland and Labrador's offshore oil fields. It attempts to account for how the environmental policy systems in these cases permit or do not prevent the environmental impacts of oil development. The theoretical frameworks of the resource curse and political ecology literatures guide this analysis within the broader context of work on petro-capitalism. I use qualitative methodologies, primarily semi-structured interviews and a review of scholarly, government, and publicly oriented literature, alongside basic economic data analysis to understand the impact of oil on these provinces. I argue that petro-political dynamics in these cases result in weak environmental policy regimes that, in turn, lead to undesirable environmental outcomes. The provinces I study are marked by the symbiotic relationship between governments and oil companies. Given shared economic interests in oil development, the provincial (and also federal) government ensures the continuation of the industry via financial subsidies, by actively defending and promoting the industry at home and abroad, and by abrogating its regulatory responsibility and authority. The oil industry simultaneously reinforces the governmental approach through coordinated lobbying efforts. The shared interests of government and industry amount to strong consent for oil developments and translate into biased environmental policy regimes: the petropolitics at work forward rapid, extensive oil development while not meaningfully restraining the resulting environmental impacts. Notable ways in which regulatory structures are weak or underdeveloped involve critical gaps in regulations and research as well as ineffective public consultation, monitoring and enforcement. However, there are viable policy alternatives available and growing oppositional movements are pressing for these changes. Building from those perspectives, the dissertation closes by presenting two paths forward. The first adjusts current policies to avoid the worst outcomes of the resource curse and to reduce environmental impacts. The second challenges the petro-political system more profoundly, suggesting alternatives that are environmentally sustainable and politically and economically just.