This paper highlights the fundamental importance of the family as a pre-political institution for moral education and a signaling mechanism for cooperation in Locke’s state of nature. Conjugal societies moderate children by teaching them to follow the law of nature. They also serve as signaling mechanisms that enable moderate individuals to trust others and collectively enforce the law of nature. The family, as a pre-political moderating institution, underpins the fragile peace in Locke’s state of nature. Contrary to common beliefs, I argue that the family makes Locke’s depiction of the state of nature more credible than Hobbes’s. This has significant implications: exegetically, it explains why individuals in Locke’s state of nature (imperfectly) follow the law of nature; normatively, it provides reasons to prefer Locke’s liberalism over Hobbes’s authoritarianism; and speculatively, it invites social contract theorists to seriously consider the extent to which liberal political institutions rely on informal institutions.