The advent of a dimensional model of personality disorder included in DSM-5 has necessitated the development of a new measurement scheme, specifically a self-report questionnaire termed the Personality Inventory for DSM-5 (PID-5; Krueger, Derringer, Markon, Watson, & Skodol, 2012 ). However, there are many threats to the validity of a self-report measure, including response inconsistency. This study outlines the development of an inconsistency scale for the PID-5. Across both college student and clinical samples, the inconsistency scale was able to reliably differentiate real from random responding. Random responses led to increased scores on the PID-5 facets, indicating the importance of detecting inconsistent responding prior to test interpretation. Thus, this inconsistency scale could be of use to researchers and clinicians in detecting inconsistent responses to this new personality disorder measure.