The MMPI-2 Malingering Discriminant Function Index (M-DFI) was designed to detect malingerers educated about MMPI-2 validity indicators. However, given current attorney practices, the clinical utility of the M-DFI lies in its ability to detect examinees who are cautioned about the indicators. In this study, we compared 45 inmate simulators cautioned to avoid detection on the MMPI-2 with 46 psychiatric inmates who completed the MMPI-2 under standard instructions. Logistic regression analyses indicated that although the M-DFI performed better than several individual indicators, results were mixed for combinations of indicators, and the M-DFI did not outperform different sets of existing indicators. These findings support existing strategies to detect malingering on the MMPI-2. We discuss considerations concerning the clinical applicability of M-DFI.