Recent evaluations by the DOE and others indicate that large quantities of biomass grown in semi-humid and humid regions are likely to be harvested and stored wet rather than in dry bales. The interaction of ensiled storage with reduced severity dilute acid pretreatment was studied. The resulting impact on hydrolysis and saccharification was examined. Results indicate ensiled storage created a favorable environment for microbial and enzymatic biocatalysis, reducing required pretreatment severity, and subsequently increasing cellulose and hemicellulose hydrolysis to sugars for ethanol fermentation. Chemical and thermal pretreatment techniques currently constitute over 30% of the costs of biomass conversion to ethanol, so integration of beneficial wet storage strategies with pretreatment could significantly increase the economic viability of cellulosic biorefineries. This is an abstract of a paper presented at the AIChE Annual Meeting (Salt Lake, UT 11/4-9/2007).