Although the 5-factor model (FFM) has been advocated as an alternative to representing the construct of borderline personality, some argue that this diagnosis carries essential information that is not well captured by the FFM. The present study examined antecedent, concurrent, and predictive markers of construct validity in a sample of 362 patients with personality disorders. The results indicated that neuroticism best distinguished borderline and nonborderline patients, whereas the FFM as a whole captured a sizable proportion of the variance in the borderline diagnosis. However, the residual of the borderline diagnosis that was not explained by the FFM was found to be significantly related to childhood abuse history, family history of mood and substance use disorders, concurrent symptoms, and 2-year and 4-year outcomes. Thus, some elements of the borderline diagnosis may not be fully captured in a 5-factor representation.