Norm talk is verbal communication that explicitly states or implicitly implies a social norm. To investigate its ability to shape cultural dynamics, 2 types of norm talk were examined: injunction, which explicitly states what should be done, and gossip, which implies a norm by stating an action approved or disapproved of by the communicator. In 2 experiments, participants engaged in norm talk in repeated public goods games. Norm talk was found to help sustain cooperation relative to the control condition; immediately after every norm talk opportunity, cooperation spiked, followed by a gradual decline. Despite the macrolevel uniformity in their effects on cooperation, evidence suggests different microlevel mechanisms for the cooperation-enhancing effects of injunction and gossip. A 3rd study confirmed that both injunction and gossip sustain cooperation by making salient the norm of cooperation, but injunction also effects mutual verification of the communicated norm, whereas gossip emphasizes its reputational implications by linking cooperation to status conferral and noncooperation to reputational damage. A 4th experiment provided additional evidence that norm talk was superior to the promise of conditional cooperation in sustaining cooperation. Implications of the findings for cultural dynamics are discussed in terms of how feelings of shared morality, language-based interpersonal communication, and ritualization of norm communication contribute to social regulation. (PsycINFO Database Record (c) 2019 APA, all rights reserved).