Patients with schizophrenia have Wisconsin Card Sorting Test (WCST) deficits, which are commonly interpreted as reflecting frontal cortex-based executive dysfunction. One means of assessing the refractoriness of frontal-executive impairment is to utilize a training or modification strategy to improve WCST performance. In this study, 73 patients with schizophrenia were assigned to 1 of 2 groups. Group 1 received the standard WCST instructions for 64 cards (Condition 1). For the second 64-card deck, the patients were asked to verbalize the reason that they placed the card where they did after each sort (Condition 2). Group 2 received this modified instruction 1st (Condition 1) and then the standard instructions for the second deck (Condition 2). A group of normal comparison participants was also tested using standard instructions alone. Group 2 committed significantly fewer perseverative responses than did Group 1. Furthermore, there was no significant difference between Group 2 (Condition 1) and the normal participants. Group 1's performance improved when patients were exposed to the modified instructions (Condition 2). Additionally, poor premorbid factors and disorganized symptoms were associated with decreased benefit from the modified instructions across both groups. Cumulatively, these data suggest that a simple instruction may enhance executive function and impact WCST performance in patients with schizophrenia. (JINS, 2001, 7, 344–352.)