The development of renewable and sustainable lignocellulosic biofuels is currently receiving worldwide attention and investment. Despite decades of research, there remain significant challenges to be overcome before these biofuels can be produced in large volumes at competitive prices. One obstacle is the lack of efficient and affordable catalytic systems to dissolve and hydrolyze polysaccharides into sugars. These sugars are then fed to microrganisms and fermented into biofuels. The price of these catalysts, be they biological, thermochemical, or chemical in nature, represent one of the largest costs in the conversion process. There are a number of catalytic schemes, each with their own advantages and disadvantages, available. This book presents a general yet substantial review of the most promising processes and the spectrum of biomass pretreatment, enzymes, chemical catalysts, and hybrid approaches of hydrolyzing biomass into fermentable sugars. It is the only currently available book that compares the biochemical, chemical, and thermochemical conversion processes to biofuel production.