This report addresses the central issue of biofuel sustainability using a global assessment of major commodities and feedstocks currently employed for bioethanol and biodiesel production. The approach taken was guided by two overriding considerations. First, the need to understand the basic dimensions of sustainability for biofuels (economic, environmental and social), their linkages and how they relate to the central challenges they address, namely land-use change, food security and climate change. Second, the need to critically evaluate the extent to which the recent trends in biofuel certification schemes reflect true sustainability versus trade flow regulation under the guise of sustainability; in other words, are the initiatives essentially market driven or sustainability motivated, or both? The report is global in scope and surveys a large number of country case studies aimed at shedding light on the sustainability issues examined. It focuses on current biofuel production systems as well as the major biofuel sustainability initiatives and certification schemes.