The global land use implications of biofuel expansion have received considerable attention in the literature over the past decade. Model-based estimates of the emissions from cropland expansion have been used to assess the environmental impacts of biofuel policies. And integrated assessment models have estimated the potential for biofuels to contribute to greenhouse gas abatement over the coming century. All of these studies feature, explicitly or implicitly, competition between biofuel feed stocks and other land uses. However, the economic mechanisms governing this competition, as well as the contribution of biofuels to global land use change, have not received the close scrutiny that they deserve. The purpose of this paper is to offer a deeper look at these factors. We begin with a comparative static analysis which assesses the impact of exogenously specified forecasts of biofuel expansion over the 2006-2035 period. Global land use change is decomposed according to the three key margins of economic response: extensive supply, intensive supply, and demand. Under the International Energy Agency’s “New Policies” scenario, biofuels account for nearly one-fifth of global land use change over the 2006-2035 period. The paper also offers a comparative dynamic analysis which determines the optimal path for first and second generation biofuels over the course of the entire 21st century. In the absence of GHG regulation, the welfare-maximizing path for global land use allocates 170 Mha to biofuel feed stocks by 2100, with the associated biofuels accounting for about 30% of global liquid fuel consumption. This area expansion is somewhat diminished by expected climate change impacts on agriculture, while it is significantly increased by a moderately aggressive GHG emissions target and by advances in conversion efficiency of second generation biofuels. Keywords: Biofuels, global land use, partial equilibrium analysis, comparative statics, comparative dynamics, climate change impacts, carbon policies.