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Steers grazing on Kansas shortgrass rangelands achieve 55% of their total season gain during the first half of the grazing season and 45% during the last half. To attain a higher rate of gain during the last half of the season, protein supplementation was implemented to improve the digestibility of late season forage. It was hypothesized that wet distillers grains plus solubles (WDGS) could be used as a replacement for a mixture of finely rolled milo and soybean meal supplement as a late season crude protein (CP) source. Steers were stocked continuously season-long at a rate of 3.5 ac/steer, or 0.95 animal unit months (AUM)/ac, from May through October. During the last half of the grazing season, animals were supplemented at 1.0 lb dry matter/hd/day with a finely rolled milo and soybean meal mix in a 1:1 ratio, with WDGS, or were fed no supplement. The milo:soybean meal mixture was fed in a bunk, while the WDGS was fed in two treatments, either in a bunk or on the ground on shortgrass vegetation. Gains during the early season in were similar among treatments before being fed supplement. During the last half of the grazing season, animal gains were greater for the WDGS supplemented groups fed in the bunk compared to the no supplement groups. All supplemented animals had similar gain. For the whole grazing season, steers fed a late season supplement gained 17-30 lb/hd more than the unsupplemented group. Animals unsupplemented on pasture had similar gain in the feedlot compared to animals supplemented on pasture. Supplement treatment did not affect available forage dry matter in pastures. Wet distillers grains plus solubles can be fed as a late season protein supplement to replace a 1:1 mix of milo:soybean meal.