This Concept examines the opportunities for the use of biomass feedstocks in the production of liquid fuels for the transportation sector of society. The cost-competitive conversion of biomass into liquid fuels involves the integration of processes that operate on lignocellulosic feeds with processes that convert specific fractions of lignocellulose. A brief description of current energy systems is given to indicate the potential contributions of biomass to replace fossil fuel feedstocks for energy production, followed by a description of current biomass-conversion technologies. Specific focus is given to promising reaction pathways and novel research opportunities for conversion of the carbohydrate fraction of lignocellulose into fuels with targeted structures.