This dissertation examines how the malleability mindset—the belief that people can change—affects support for punishment. Prior research shows that mindset influences moral reasoning and punitiveness, yet little attention has been given to its moderating role in the link between justice motives or gender and punishment. One goal is to test whether mindset moderates the effect of justice motives. While a malleable mindset generally reduces punitiveness, it may increase support for punishment when utilitarian motives are salient, as punishment can be seen as a tool for future influence. Conversely, a fixed mindset may strengthen retributive motives, which focus on past wrongdoing. A second goal is to explore gender. Men typically show stronger support for punishment than women, but this gap appears larger under a fixed mindset and weaker under a malleable one. Three lines of research addressed these issues by manipulating or assessing either individual- or group-level malleability. Studies on collective punishment examined beliefs about group change, while a third study focused on offender punishment and individual change. Results showed that utilitarian (but not retributive) motives increased support for punishment under a malleable mindset, and that men were more punitive than women under a fixed mindset, but not under a malleable one. Limitations, implications, and future directions are discussed.