Editor's Summary: Alternative fuels such as ethanol are taking center stage as the United States searches for environmentally friendly sources of energy that will reduce dependence on foreign oil. Both the Energy Policy Act of 2005 and President Bush's "Twenty in Ten" plan express a commitment to ethanol. In this Article, Jocelyn D'Ambrosio compares ethanol fuels with gasoline. She evaluates each fuel's ability to reduce greenhouse gas emissions, its net energy balance, and its potential effect on future innovation. She concludes that corn ethanol will provide a moderate reduction in emissions, but its production is not as efficient as ethanol from woody plants (cellulosics). She therefore recommends that policymakers encourage cellulosic production, while seeking flexible policies that will not thwart more effective future innovations in alternative sources of energy.