Recent research has focused on the disparate mechanisms that support the human ability to “mentalize” about the thoughts and feelings of others. One such process may rely on precompiled, semantic beliefs about the characteristics common to members of a social group, that is, on stereotypes; for example, judging that a woman may be more likely than a man to have certain interests or opinions. In the current study, we identified a pattern of neural activity associated with the use of stereotypes to judge another person's psychological characteristics. During fMRI scanning, participants mentalized about the likely responses of a female and male target to a series of questions, some of which were related to gender stereotypes (e.g., “enjoys shopping for new clothes”). Trials on which participants applied a stereotype were segregated from those on which participants avoided stereotype use. The BOLD response in an extensive region of the right frontal cortex differentiated stereotype-applied from -unapplied trials. Moreover, this neural difference was correlated with a behavioral index of gender associations—the Implicit Association Test—administered after scanning. Results suggest that stereotype application may draw on cognitive processes that more generally subserve semantic knowledge about categories.