Lignocellulosic biomass such as agricultural and forestry residues and dedicated crops provides a low-cost and uniquely sustainable resource for production of many organic fuels and chemicals that can reduce greenhouse gas emissions, enhance energy security, improve the economy, dispose of problematic solid wastes, and improve air quality. A technoeconomic analysis of biologically processing lignocellulosics to ethanol is adapted to project the cost of making sugar intermediates for producing a range of such products, and sugar costs are predicted to drop with plant size as a result of economies of scale that outweigh increased biomass transport costs for facilities processing less than about 10,000 dry tons per day. Criteria are then reviewed for identifying promising chemicals in addition to fuel ethanol to make from these low cost cellulosic sugars. It is found that the large market for ethanol makes it possible to achieve economies of scale that reduce sugar costs, and coproducing chemicals promises greater profit margins or lower production costs for a given return on investment. Additionally, power can be sold at low prices without a significant impact on the selling price of sugars. However, manufacture of multiple products introduces additional technical, marketing, risk, scale-up, and other challenges that must be considered in refining of lignocellulosics.