The present invention relates to methods for degrading a lignocellulosic material, comprising: treating the lignocellulosic material with an effective amount of one or more. cellulolytic enzymes in the presence of at least one surfactant selected from the group consisting of a secondary alcohol ethoxylate, fatty alcohol ethoxylate, nonylphenol ethoxylate, tridecyl ethoxylate, and polyoxyethylene ether, wherein the presence of the surfactant increases the degradation of lignocellulosic material compared to the absence of the surfactant. The present invention also relates to methods for producing an organic, substance, comprising: (a) saccharifying a lignocellulosic material with an effective amount of one or more cellulolytic enzymes in the presence of at least one such surfactant; (b) fermenting the saccharified lignocellulosic material of step (a) with one or more fermentating microoganisms; and (c) recovering the organic substance from the fermentation.