Technical Abstract: The enzymes that break down the components of lignocellulosic biomass play an important role in the production of value-added chemical feedstocks and biofuels. In order to accommodate the variety of substrates and industrial process conditions, enzymes with diverse activity profiles are required. These enzymes are encoded by genes obtained either through screening of microorganisms or genetic engineering of cloned genes by techniques such as directed evolution. Both of these strategies require activity assays that facilitate the screening of many recombinants to isolate those with the desired characteristics. In this manuscript, activity assays for enzymes that degrade cellulose and hemicellulose (specifically xylan) are described for analyzing samples at various throughputs.