C4 grasses are among the most productive plants and most promising cellulosic biofuel feedstocks. Successful implementation of cellulosic biofuel feedstocks will depend on the improvement of critical crop characteristics and subsequent conversion technologies. The content and composition of lignin, cellulose, and hemicellulose, their biomass yields, and their biotic and abiotic stress tolerances are critical factors which can be enhanced by molecular breeding methods, including marker-assisted selection and transgenic approaches. To maximize biomass yield, no flowering or late flowering and no grain set would be ideal for cellulosic biofuel crops. Reducing fecundity also reduces the risk of undesired gene transfer and invasiveness, thus accelerating deregulation processes and permitting faster implementation of highly improved genotypes in cellulosic feedstock production.