We quantify the emergence of biofuel markets and its impact on world agriculture using the multimarket, multicommodity international FAPRI model. The model incorporates trade-offs between biofuel, feed, and food production and consumption and international feedback effects of the emergence through world prices and trade. We shock the model with exogenous changes in ethanol demand, first in the United States, then in Brazil and other countries, and compute shock multipliers for land allocation decisions for important crops and countries. The Brazilian ethanol expansion using sugarcane has fewer consequences on existing arable land allocation than the U.S. ethanol expansion does using corn feedstock.