This study examined the relationship between school absences and neuropsychological functioning in a group of adolescents who developed diabetes mellitus after the age of 5 years, and a demographically-similar group of non-diabetic teenagers. The diabetic group missed significantly more school, performed more slowly on a series of visuomotor tasks, and obtained lower scores on tests of reading, spelling, and arithmetic achievement. Multiple regression analyses demonstrated that the cognitive measures were differentially affected by the demographic and school attendance variables. Achievement test performance was best predicted by measures of school attendance, whereas visuomotor test performance was best predicted by demographic characteristics (grade and sex). These results imply that the somewhat lower scores earned by many diabetic youngsters on tests of general knowledge may have a psychosocial basis.