This study addresses longitudinal, expert, all data (LEAD) validity and reliability of the personality functioning ratings in Turkey, which are essential in assessing Criterion A for the entire DSM-5 alternative model for personality disorders (AMPD) diagnoses. A total of 120 consenting patients recruited at a university psychiatry clinic were rated by individual clinicians with respect to DSM-III-R and AMPD criteria. Subsequently, a LEAD panel consisting of 3 senior clinicians convened to reach a consensus personality disorder diagnosis for each participant. Blind personality functioning ratings of a subgroup of 20 participants by the same set of 4 clinicians were obtained for test-retest reliability investigation. Concordance between the LEAD and AMPD diagnoses was as good as that between the LEAD and DSM-III-R diagnoses (kappas = .68). The personality functioning scores correlated strongly (r > .50) with the sum of specific DSM-III-R diagnoses. Reliability estimates pertaining to the personality functioning scores and resultant AMPD Criterion A decisions were mostly in the good range. In conclusion, DSM-5 alternative model-oriented personality functioning ratings yield total or composite scores that are evidently valid and reliable tools to diagnose general personality disorder and to estimate its global severity.