In "DSM-5" there has been a move to dimensional personality disorder (PD) diagnosis, incorporating personality theory in the form of the five-factor model (FFM). It proposes an alternative assessment system based on diagnostic indicators and the FFM, while retaining "DSM-IV" categorical criteria. Four individuals with intellectual disability are assessed for PD utilizing the Assessment of Global Personality Functioning Index (AGPF), the International Personality Disorder Examination (IPDE), and, in terms of the FFM, through an adapted version of the NEO-PI short form. PD ratings (self, staff, and observer) tended to converge for borderline, antisocial, and narcissistic PDs. NEO-PI ratings converged on Neuroticism, Extraversion, and Openness, with discrepancies on Agreeableness and Conscientiousness (staff rating lower). A structured "DSM-5" system is easily usable but takes more time than a diagnostic interview.