We investigated the effects of systematic changes in levels of treatment integrity by altering errors of commission during error-correction procedures as part of discrete-trial training. We taught 3 students with autism receptive nonsense shapes under 3 treatment integrity conditions (0%, 50%, or 100% errors of commission). Participants exhibited higher levels of performance during perfect implementation (0% errors). For 2 of the 3 participants, performance was low and showed no differentiation in the remaining conditions. Findings suggest that 50% commission errors may be as detrimental as 100% commission errors on teaching outcomes. (Contains 1 figure and 1 footnote.)