Measurement Invariance of Three Versions of the Pathological Narcissism Inventory across Gender-Matched Italian Adolescent High School and Young Adult University Students

To assess the measurement invariance of the three versions of the Pathological Narcissism Inventory (PNI) across adolescent and young adult participants, 678 Italian adolescent high school students (M = 16.83 years old, SD = 1.85 years) and 678 adult university students (M = 23.99 years old, SD = 2.60 years) matched on gender, civil status, and geographic area, were administered the Italian translation of the original 52-item PNI. The PNI, the Brief-Pathological Narcissism Inventory (B-PNI), and Super Brief-Pathological Narcissism Inventory (SB-PNI) scales all showed adequate reliabilities in both adolescent and young adult samples. In both samples, robust maximum likelihood confirmatory factor analysis indicated that covariation among the PNI/B-PNI first-order scales, as well as among the SB-PNI items, could be adequately explained by two-correlated factors operationalizing narcissistic grandiosity (NG) and narcissistic vulnerability (NV), respectively. Multiple-group confirmatory factor analyses supported scalar invariance for both B-PNI and SB-PNI NG and NV factors, and metric invariance for the PNI NG and NV factors.