Persons with mental retardation often exhibit greater interference in visual selective attention tasks than do persons matched with them on CA. My goal here was to evaluate whether differences in distractor interference between persons with and without mental retardation may be related to differences in negative priming. Fifteen participants with mental retardation, 15 without mental retardation matched on CA, and 15 without mental retardation matched on MA participated in three selective attention tasks, which were chosen to elicit small, medium, and large group differences in interference, respectively. The failure to engage in inhibitory processes by the participants with mental retardation in these tasks of selective attention was related to increased distractor interference.