Live performance to 96 d was compared for 1,584 turkey toms reared on diets containing four levels of whole barley and two levels of insoluble grit (0 or 9 g/bird per wk). Nutrient specifications for all diets were similar. The six dietary treatments were 1) 0% whole barley plus grit, 2) Treatment 1 minus grit, 3) grit plus 5% whole barley at 0 d increasing to 35% by 19 d, 4) grit plus 59% whole barley at 0 d increasing to 50% by 19 d, 5) Treatment 4 minus grit, and 6) grit plus 5% whole barley at 19 d increasing to 50% by 40 d. The concentrate blended with the whole barley was fed as crumbles or pellets. Nutrients were not diluted. Compared to the control treatments, feeding 35%, or more whole barley temporarily reduced weight gain and increased feed:gain prior to 68 d. Cumulative weight gain was reduced in Treatments 3 and 5 compared to treatments in which no barley was fed. Cumulative feed:gain was increased in Treatment 5 compared to Treatments 2 and 3. Total mortality and leg and skeletal problems were reduced in treatments where whole grain slowed early growth rate. Feeding grit had no effect on the live performance of birds fed similar levels of whole barley. In treatments in which whole barley was introduced at 0 d, gizzard pH was decreased at 18 d, and gizzard weight was increased at 32 d. Jejunal viscosity was unaffected by dietary treatment.