Four-year-olds, 5-year-olds, and adults (N = 48) listened to stories featuring characters that experienced one of four types of thoughts after deciding to transgress or comply with a rule: thoughts about desires, rules, future negative outcomes, or future punishment. Participants predicted and explained the characters' emotions. Results showed that young children, as with adults, predicted positive emotions for willpower and negative emotions for transgression at low rates for the think-desire trials, and at high rates for the think-rule and think-future trials. They also modified their emotion explanations in line with the focus of characters' thoughts. These data provide unprecedented evidence that young children can reason flexibly about emotions in rule situations when provided explicit, salient information about people's thoughts.