A large pen study was conducted with a commercial feedlot to investigate the influence of corn particle size on performance of steers fed diets containing 35% (DM basis) wet distillers grains plus solubles (WDGS). Feedlot cattle in the Midwest are often fed distillers grains from ethanol production that are low in starch. Therefore, this study was designed to evaluate a practical question asked by producers if feeding moderate levels of WDGS would reduce the acidosis risk and allow fine grinding of corn to improve cattle performance. While fine grinding of corn did not improve performance compared to cattle fed a more traditional particle size of corn, starch digestibility of cattle fed finely ground corn was more favorable.