This essay is a Neo-Aristotelian critique of Frans de Waal’s evolutionary moral sentimentalism. For a sentimentalist, moral judgments are rooted in reactive attitudes such as empathy, and De Waal argues that higher primates have the capacity for empathy—they can read other agent’s minds and react appropriately. De Waal concludes that the building blocks of human morality—primarily empathy—are present in primate social behavior. I will engage de Waal from within the sentimentalist tradition itself broadly construed and the Aristotelian virtue tradition more specifically. Within an Aristotelian framework, emotion regulation is necessary for moral responsibility. Aristotle understands that emotions are evaluative perceptions with cognitive content, and non-human animals do not possess the cognitive capacities for emotion regulation and are thus not morally responsible. This marks a boundary between primate behavior and human morality.