The advances in information technologies and the Internet significantly promote the prosperous growth of electronic commerce in recent years. Simply surfing the Internet allows consumers to conveniently explore endless product choices and a flood of related product information. As one of the most important sources of product information, Word-of-Mouth (WOM) helps consumers assess product quality, reduces decision risk without physical trials, and thus facilitates locating their best matches. WOM volume on the Internet has been rising fast while the Internet also unprecedentedly enhances the reach of WOM. As a result, online WOM could significantly influence consumer decision-making. More and more firms are embracing and applying online WOM marketing as a complementary strategy for advertising to increase sales. Even so, not much has been known regarding the mechanism underlying the WOM effect on online consumer behavior. A deeper understanding of the economic impact of online WOM is needed to provide practitioners insightful guidance on information systems design and the allocation of firm resources to more effectively develop online WOM marketing strategies.