The primary goal of this study was to explicate the construct validity of the Narcissistic Personality Inventory (NPI) and the Hypomanic Personality Scale (HPS) by examining their relations both to each other and to measures of personality and psychopathology in a community sample (N = 255). Structural evidence indicates that the NPI is defined by Leadership/Authority, Grandiose Exhibitionism, and Entitlement/Exploitativeness factors, whereas the HPS is characterized by specific dimensions reflecting Social Vitality, Mood Volatility, and Excitement. Our results establish that (a) factor-based subscales from these instruments display divergent patterns of relations that are obscured when relying exclusively on total scores and (b) some NPI and HPS subscales more clearly tap content specifically relevant to narcissism and mania, respectively, than others. In particular, our findings challenge the construct validity of the NPI Leadership/Authority and HPS Social Vitality subscales, which appear to assess overlapping assertiveness content that is largely adaptive in nature.