Children want to be fair, and they acquire a sense of justice at a very young age: they quickly learn that hurting other people is wrong and that sharing is right. But this developing sense of morality can conflict with their developing sense of belonging. Children readily pick up on us-versus-them group identities based on factors such as race and gender. Psychologist Melanie Killen describes what she and her colleagues have learned about morality and prejudice in children. Based on their research, they created a training program that successfully teaches kids to be more inclusive and empathetic.