Cellulases comprise an important group of enzymes involved in several industrial processes. In recent years they are especially being used in the lignocellulosic biomass conversion into small sugars to produce cellulosic ethanol and chemicals. Filamentous fungi are the most important producers of these catalysts. In order to increase cellulase yield and reduce the production costs, many strategies are being applied such as, submerged fermentation or solid state fermentation using waste residues, aligned with advanced molecular techniques to improve the enzymes performance, reducing its amounts in industrial process as well as the time required by its production. Thus, this chapter will present some of the most important procedures to scale up cellulase production to enable second generation industry.