Valid self-report assessment of psychopathology relies on accurate and credible responses to test questions. There are some individuals who, in certain assessment contexts, cannot or choose not to answer in a manner typically representative of their traits or symptoms. This is referred to, most broadly, as test response bias. In this investigation, we explore the effect of response bias on the Personality Inventory for DSM-5 (PID-5; Krueger, Derringer, Markon, Watson, & Skodol, 2013 ), a self-report instrument designed to assess the pathological personality traits used to inform diagnosis of the personality disorders in Section III of DSM-5. A set of Minnesota Multiphasic Personality Inventory Restructured Form (MMPI-2-RF; Ben-Porath & Tellegen, 2008 / 2011 ) validity scales, which are used to assess and identify response bias, were employed to identify individuals who engaged in either noncredible overreporting (OR) or underreporting (UR), or who were deemed to be reporting or responding to the items in a "credible" manner-credible responding (CR). A total of 2,022 research participants (1,587 students, 435 psychiatric patients) completed the MMPI-2-RF and PID-5; following protocol screening, these participants were classified into OR, UR, or CR response groups based on MMPI-2-RF validity scale scores. Groups of students and patients in the OR group scored significantly higher on the PID-5 than those students and patients in the CR group, whereas those in the UR group scored significantly lower than those in the CR group. Although future research is needed to explore the effects of response bias on the PID-5, results from this investigation provide initial evidence suggesting that response bias influences scale elevations on this instrument.