Neuropsychological functioning has not yet been investigated among prisoners who engage in self-injurious behaviors, specifically attempted suicide and nonsuicidal self-injury (NSSI). The purpose of this study was to investigate neuropsychological functioning in prisoners with and without histories of NSSI and attempted suicide. The sample consisted of 173 male prisoners referred for neuropsychological evaluation. Of participants, 56% reported a history of self-injury. Performance on the neuropsychological domains of intelligence, memory, attention, motor functioning, and executive functioning was assessed. No group differences were found among those with NSSI, with NSSI and suicide attempts, and with no history of deliberate self-harm, although functioning was poor in all domains. Implications of the high prevalence of self-injury in this prison sample, as well as implications of impaired functioning on the treatment of self-injurious behaviors, are discussed.