It has been posited that extremely high or extremely low levels of any personality trait in the five-factor model can be maladaptive. However, the Alternative Model of Personality Disorders in Section III of the Diagnostic and Statistical Manual of Mental Disorders-fifth edition (DSM-5) is composed almost exclusively of unipolar maladaptive traits. The lack of maladaptively low neuroticism and high extraversion fails to fully cover psychopathy; the lack of maladaptively high extraversion fails to cover histrionic personality disorder; the lack of maladaptively high agreeableness fails to cover dependent personality disorder; and the lack of maladaptively high conscientiousness fails to cover obsessive-compulsive personality disorder. The goal of this study was to discern whether Five-Factor Model Personality Disorder (FFMPD) scales demonstrate incremental validity over the Personality Inventory for DSM-5 (PID-5) in capturing variance in symptom measures of each of these personality disorders. A combined sample of N = 733 completed an online questionnaire battery that included the PID-5 and FFMPD scales for psychopathy, histrionic personality disorder, dependent personality disorder, and obsessive-compulsive personality disorder, along with symptom measures for each of these conditions. A series of hierarchical regression models was conducted in which each symptom measure was regressed on the PID-5 (entered in Step 1) and the corresponding FFMPD measure (entered in Step 2). Results suggest that adding the FFMPD measure to the models accounted for significantly more variance in its corresponding symptom measure than the PID-5 alone. Taken together, these results suggest that maladaptive variants of personality traits that are often considered healthy (e.g., low neuroticism, high extraversion) confer important information about personality disorder symptoms and functioning and should be included in the Alternative Model of Personality Disorders. (PsycInfo Database Record (c) 2026 APA, all rights reserved).