Objective: To explore whether depressive-symptom severity alters the ability of intelligence scales on the WAIS-IV to predict set-shifting performance on the Wisconsin Card Sort Task (WCST). Method: Complete test scores from 243 participants representing a mixed clinical sample in a de-identified community clinical neuropsychology database in South Florida were analyzed (46.5% male). A backwards-stepwise linear regression model at the .001 level predicting WCST errors (or perseverative errors) from t-transformed core WAIS-IV scales was compared to an expanded model with original predictors and Beck Depression Inventory (BDI) and multiplicative interaction terms between WAIS-IV and BDI in a second step for each WCST score. Results: At the .001 level, the model without depression terms predicting WCST errors was significant, F(10,232) = 49.37, Radj2 =.18, PIQ was a significant model predictor (p < .001), though the change in F was not significant (p = .021); the model with depression terms was significant, F(10,232) = 27.70, Radj2 =.19. BDI and BDI*PIQ were significant model predictors (p < .001), though the change in F was not significant (p = .049). The models without depression terms predicting WCST perseverative errors was significant, F(10,232) = 25.15, Radj2 =.10. WMIQ was a significant model predictor (p < .001), though the change in F was not significant (p = .011); the model with depression terms was significant, F(10,232) = 18.57, Radj2 =.077., with BDI*PIQ a model predictor (p < .001) and the change in F statistically significant (p = .003). Conclusion: Depression severity appears to increase perseveration to greater degree when perceptual reasoning skills are poor, due to interference with non-verbal reasoning and not attention, speed, or memory. Intelligence scores and depression were weak predictors. Results suggest a subtle relationship between depression and perseveration, but not accuracy. Future research should explore whether depression impairs performance on other tests measuring nonverbal executive function.