Assessments were conducted to identify preferred foods for 9 adults with severe to profound mental retardation. Subsequently, the reinforcing effects of each participant's most highly preferred food were evaluated during sessions conducted before and after lunch. Results showed that 4 participants' response rates were higher during premeal sessions than during postmeal sessions. By contrast, pre- and postmeal response rates were indistinguishable for the other 5 participants. These results indicate that the reinforcing efficacy of food may (but does not necessarily) diminish following meals and suggest that the influence of meal schedules should be examined on an individual basis when food is used as reinforcement during training sessions.