In my research, I explore the underpinnings of human morality and cooperation. Humans are inordinately cooperative beings, and our ultra-cooperative, moral nature is thought to account for our success as a species. My research focuses on the ontogenetic emergence of the moral emotions, cognitions, and behaviors that make children successful cooperators. This includes the emergence of social emotions such as sympathy, guilt, and forgiveness; of moral evaluations of one's own and others' actions; and of moral behaviors such as helping, sharing, and the enforcement of moral norms. I have also recently begun examining more uncooperative phenomena, such as cheating and reputation enhancement, in order to expand our understanding not only of when and why cooperation works but also of when and why it doesn’t.