The Perrotta Integrative Clinical Interview, second version (PICI-2) requires structural and functional updates, based on clinical and academic experience, especially in terms of functional traits and interpretation of psychopathological disorders. The Perrotta Integrative Clinical Interviews-3 (PICI-3) was createdand structured into foursections, dedicated to dysfunctional traits in children and pre-adolescents (PICI-C-3, 8-13 years) and in adolescents, adults, and the elderly (PICI-TA-3, 14-90 years), to common secondary disorders (PICI-DS-3, 8-90 years) and functional traits (PICI-FT-3, 8-90 years), with the identification of all functional elements and structural aspects of personality according to the model underlying the PICI (IPM). Selecting 1732 subjects, between 8 and 90 years old, the statistical analysis showed that the psychometric test has a well-defined and stable construct, with the variables well represented and positively correlated with other constructs already validated. In particular: (a) the PICI-TA-3 (Section A) was compared with the Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF), obtaining 99.3% compatibility of results, with a Pearson's coefficient (R) of 0.999 and p < 0.001; (b) the PICI-C-3 (Section B) was compared with the Child Behavior Checklist (CBCL), obtaining 94.1% compatibility of results, with a Pearson coefficient (R) of 0.969 and p < 0.001; (c) the PICI-FT-3 (Section D) was compared with the Big Five Personality Test (Big5), obtaining 89.4% compatibility of results, with a Pearson coefficient (R) of 0.797 and p < 0.001. The PICI-3 is a valid, efficient, and effective psychometric tool to identify the functioning or dysfunction of personality traits for psychopathological diagnosis.