What motivates targets of prejudice to confront people who express explicit bias? This dissertation reports the results of eight studies investigating this question. In the first three studies, I tested the hypothesis that targets who hold an incremental theory of personality (i.e., the belief that people can change) are more likely to confront prejudice than targets who hold an entity theory of personality (i.e., the belief that people have fixed traits). In Study 1, targets' implicit theories predicted whether they spontaneously confronted an individual who expressed bias. Study 2 replicated this effect and showed that incremental theorists were less likely to anticipate withdrawing from future interactions with an individual who expressed prejudice. In Study 3, I manipulated implicit theories and replicated these findings. Next, I explored one potential explanation for why. I tested the hypothesis that incremental theorists would be more likely to view confronting as effective in creating change than entity theorists, even if both did so. In Study 4, targets who held a more incremental theory reported being more likely to confront prejudice and anticipated their behavior to be more effective. Study 5 elicited African American adults' retrospective accounts of encounters with bias while Studies 6-7 used a hypothetical scenario to expose participants to evidence of someone who had expressed bias either remaining the same or changing over time. The pattern of results across these studies revealed that even when entity and incremental theorists enact the same (actual or anticipated) confronting behavior, it is exclusively the incremental theorists who view this behavior as more efficacious. Study 8 investigated whether implicit theories play a causal role in perceptions of the efficacy of confronting. All targets expressed disagreement with a biased statement, but those in the incremental theory condition expressed the belief that speaking up would create change to a significantly greater degree than did those in the entity theory condition. By highlighting the central role that implicit theories play in targets' motivation to confront prejudice and their perceptions of whether confronting is effective, this research has important implications for intergroup relations and social change.