College students' processing of alcohol, smoking, and exercise social norms messages, and related effects on judgments, attitudes toward one's own behaviors, and attitudes toward undergraduates' behaviors were examined using social norms marketing and Expectancy Violation Theory (EVT) (N = 393). Receiving statistical social norms messages led to an expectancy violation of the perceived social norm (i.e., a discrepancy between the expected and actual statistic conveyed with a message). Consistent with Boster et al. (2000), the effect of the message discrepancy on attitudes was mediated by judgments. In accordance with social norms, when participants were provided with a statistic, the majority moved their judgments (but not their attitudes) toward the provided statistic, a result only consistent with EVT in the case of positive violations. The results have multiple implications: (1) social norms messages may work to change judgments, but do not result in consistent attitude change; (2) the process of judgment change functions similarly across message topics, as well as message types (i.e., attitudinal versus behavioral); (3) judgment change does not appear to be the main cause for attitude change upon receipt of a social norms message; and (4) a message-based expectancy violation does not function in the same way as a violated behavioral expectation.