Punishment is a key mechanism to regulate selfish behaviors and maintain cooperation in a society. However, children often show mixed evaluations about third-party punishment. The current work asked how punishment severity might shape children's social judgments. In two studies, 5- to 10-year-old children heard about a punisher who took different numbers of items from a transgressor and evaluated the punisher's behavior and moral character. In Study 1 (n = 68), when the transgression was relatively mild (i.e., unfair sharing), children across ages evaluated taking no items from the unfair sharer ("no punishment") most positively, while evaluating taking three items ("harshest punishment") most negatively. In Study 2 (n = 68), when the transgression was more serious (i.e., stealing), younger children evaluated taking two items ("equality-establishing punishment") more positively than older children, while evaluating taking none most negatively. However, children became more likely to evaluate equality-establishing punishment negatively with age. Overall, the current results show that punishment severity is a key factor underlying children's third-party punishment judgments. The current research extends work on moral development by showing how children conceptualize the severity of punishment. (PsycInfo Database Record (c) 2024 APA, all rights reserved).