The DSM-5 Section III model of personality disorders remains largely unexplored in older adults. More specifically, there is a need for further research on the generalizability of the five trait domains in old age. The development of a short operationalization to screen for maladaptive trait domains, the Personality Inventory for DSM-5 Brief Form (PID-5-BF), can stimulate the use of the alternative DSM-5 model in older adults by addressing the need for short instruments. The primary goal of this study was to examine the construct validity of the PID-5-BF by comparing its structural model and nomological network with the original PID-5 in terms of relations with domains of personality functioning and a gero-specific personality disorder indicator. A five-factor model was supported, but the domain Disinhibition was not replicated in the original PID-5, and some PID-5-BF items showed weak loadings. Nevertheless, the nomological network was similar and showed meaningful relations, supporting the use of the Brief PID-5 in older clinical samples.