Work on cultural evolution, especially that of Boyd, Richerson, and Henrich, has said little about the role of reinforcement in cultural learning. This is surprising, for reinforcement is an old system, it is found across a diverse array of organisms, and it is a successful concept in various scientific disciplines. The main claim of this paper is that social forms of reinforcement play a role in cultural evolution. More specifically, I argue that starting early in human history, social approval and disapproval of behavior function as reinforcers and punishers; approval and disapproval thereby start a process whereby norms are transmitted. After giving arguments for these claims, I discuss work on social learning strategies—cultural rules s...