Neonatal intensive-care unit (NICU) graduates, a group at risk for attention problems and attention-deficit hyperactivity disorder, performed an intradimensional shift card sort at 34, 42, 51, and 60 months to assess executive function and to examine effects of individual risk factors. In the "silly" game, children sorted cards (airplanes and dogs) so they were not the same as targets. In the "same" game, they did the opposite. Performance on the "silly" game was poor, especially when it was presented first. Success in following "silly" game rules improved with age and was significantly linked to maternal education and birth weight for gestational age, a measure of intrauterine stress. Degree of central nervous system injury differentiated children who completed the task from children who did not, and it also affected the need to repeat instructions in the "same" game. These results confirm an increased likelihood of impairments in executive function during preschool years in NICU graduates.