Shock treatment is a novel mechanical pretreatment process that, when combined with oxidative lime pretreatment, greatly increases the digestibility of biomass. This work determined the effectiveness of shock treatment on multiple feedstocks (sugarcane bagasse, corn stover, poplar wood, sorghum, and switchgrass), determined recommended shock treatment conditions for corn stover, and compared cellulose crystallinity and copper number of raw and shock-treated samples. At an enzyme loading of 5 FPU/g raw glucan, the combination of oxidative lime pretreatment (OLP) and shock treatment increased 72-h glucan digestibility (g glucan digested/100 g glucan treated) of corn stover from 15.3 (untreated) to 84.6 (OLP + shock). The other four biomass types showed similar gains in glucan digestibility when compared to the respective untreated biomass: + 55.7 (bagasse), + 76.3 (poplar wood), + 48.2 (sorghum), and + 73.1 (switchgrass). Recommended shock treatment conditions show that a single shock at room temperature with never-frozen biomass produces the most digestible corn stover.