Objective: This study examined the extent to which demographic variables (i.e., age, education, premorbid IQ, sex, ethnoracial identity, and presence/absence of external incentive) affect performance validity test (PVT) performance. Method: This cross-sectional study examined two distinct, diverse outpatient clinical samples at an academic medical center (AMC, N = 268) and a Veterans Affairs (VA) medical center (N = 111). All patients completed a battery including five PVTs. Premorbid IQ was assessed using the Test of Premorbid Functioning (TOPF) in the AMC sample. Results: Multiple correlations between demographic variables and individual PVT performance were statistically significant, but accompanying effect sizes were small, except for the relationship of premorbid IQ and reliable digit span (RDS). Regressions showed demographic variables accounted for 7%–11% of the variance in individual PVT scores in the AMC sample, and 6%–26% in the VA sample, premorbid IQ driving results in the AMC sample and compensation-seeking status in the VA sample. Other demographic variables did not correlate with compensation-seeking status. Additionally, premorbid IQ was found to be significantly higher in validly performing individuals compared to those performing invalidly in the AMC sample. Conclusion: Most demographic factors evaluated accounted for relatively little variance in individual PVT performance and did not significantly predict overall validity categorization. Compensation-seeking status correlated with validity classification across both groups, but offers limited diagnostic utility itself compared to objective PVT scores. Premorbid IQ within the AMC group demonstrated influence on particular PVTs (i.e., RDS) reflecting the difficulty of assessing validity within low IQ populations, particularly with PVTs more strongly correlated with IQ.