In the article “Subunit-Selective Modulation of GABA Type A Receptor Neurotransmission and Cognition in Schizophrenia” by David A. Lewis, M.D., et al. (Am J Psychiatry 2008; 165:1585–1593), there was an error in Table 4 in the reported between-group effect sizes for the Preparing to Overcome Prepotency task. As indicated in the Method section, the authors ran MANOVAs for the N-back and Preparing to Overcome Prepotency task on the nine subjects receiving MK-0777 and the five placebo subjects that had complete data for both tasks (i.e., one placebo subject did not complete the N-back task). The effect sizes reported in Table 4 (reaction time: 1.74; error rate: –0.35) were calculated from these data, and the same effect sizes were mentioned in the text. However, the mean and SD values reported for the Preparing to Overcome Prepotency task in Table 4 are from all six placebo subjects. With these data, the effect sizes change (reaction time: 1.10; error rate: –0.63). In addition, in the Results section, under Cognitive tasks, 3rd paragraph, 3rd line, the numbers in parentheses should be changed to (0.83–1.10). These changes do not affect the interpretation of the findings or other aspects of the paper.