Based on the collaborative and social characteristics, social networking services (SNSs) are growing platforms for consumer-to-consumer conversation including electronic word-of-mouth (eWOM). eWOM is defined as ‘any positive or negative statement made by potential, actual, or former customers about a product or company, which is made available to a multitude of people and institutions via the Internet’ (Hennig-Thurau, Gwinner, Walsh, & Gremler, 2004, p.39). Despite its academic and managerial significance, several preliminary studies have examined what determines effective eWOM in SNSs (e.g., Chu & Kim, 2011; Teng, Khong, Goh, & Chong, 2014). Extending these attempts, we empirically investigate what influences consumers’ evaluation of eWOM, especially on Facebook. We suggest a new perspective of focusing on the psychological stream of social identity (Tajel & Turner, 1986) which is a distinctive factor explicit on Facebook. Unlike conventional eWOM platforms like bulletin boards and online communities where the user information is limited due to anonymity or presented in restricted manner (e.g., reputation from ratings by other members) (Dou, Walden, Lee, & Lee, 2012), Facebook provides profile information about users including one’s social group membership (e.g., school, company). This implies that the perception of social identity on Facebook may influence how one evaluates the source and his/her eWOM message.