Cellulase refers to a class of enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis. This volume of Methods in Enzymology comprehensively covers this topic. With an international board of authors, this volume covers subjects such as "The DNSA reducing assay for measuring cellulases," "Measuring processivity" and "In situ cellulose detection with carbohydrate-binding modules."