Reducing dependence of any country on imported crude oil is of critical importance for long-term security and continued economic growth. Supplementing crude oil consumption with renewable biomass resources is a first step towards this goal. The realignment of the chemical industry from one of petrochemical refining to a bio-refinery concept is, given time, feasible has become a national goal of many oil-importing countries. However, clearly defined goals are necessary for construction of a biorefinery and the increasing the use of biomass-derived feedstocks in industrial chemical production and it is important to keep the goal in perspective. In this context, the increased use of biofuels should be viewed as one of a range of possible measures for achieving self-sufficiency in energy, rather than a panacea. A biorefinery is the means by which biomass can be converted to other products – in the current context the other products are biofuels which have the potential to replace certain crude oil-derived fuels. One aspect of designing a refinery for any feedstocks is the composition of the feedstocks. For example, a heavy oil refinery would differ from a conventional refinery and a refinery for tar sand bitumen would be significantly different to both. Similarly, and because the chemical and physical composition of biomass is variable, there is no obvious simple design panacea for a biorefinery. The variation in the properties of biomass feedstocks dictates that different process options will be necessary in the near-term for converting biomass to hydrocarbon products (chemicals) and to biofuels. This chapter presents the different biomass feedstocks that might be used in a biorefinery and offers descriptions of the various conversion options.