The biofuel industry has been experiencing a period of extraordinary growth, fueled by a combination of high oil prices, ambitious renewable fuel standards, subsidies, and import protection. This rapid growth has important consequences for the US and global economies. In this paper, we examine these consequences from partial and general equilibrium perspectives. We first examine US biofuel policy backgrounds to determine factors which caused the boom in the ethanol industry in recent years. Then we use a partial equilibrium model to investigate the economic consequences of further expansion in the ethanol industry for the key economic variables of the US agricultural and energy markets under alternative policy options which might be used to promote ethanol production in the future. Finally, we extend our analyses to examine consequences of further biofuel production at a global scale. One of the important conclusions of the research regards the importance of the link between energy and agricultural markets that has now come into being. That linkage has profound implications for the agricultural sector globally.