It is common practice to have Websites interact with consumers by delivering personalized services, among which content relevance is most widely adopted on Internet advertising. However, little is known about the impact of relevance on consumers’ psychological states and the underlying mechanism of relationship between relevance and attitude toward Websites. Building upon flow theory and Hoffman and Novak’s (1996) conceptual model, this study investigates the role of flow and relevance in influencing attitude toward Websites. The findings show that the link between content relevance and attitude toward Web sites is mediated by consumers’ flow experience. In addition, goal specificity moderates the effect of relevance on flow experience. Under the conditions of high goal specificity, the relevance effect on flow is magnified. Theoretical and practical implications of this study are discussed.