The number of peers (peer network externalities) and perceived complementarity (indirect network externalities) are more influential on extrinsic benefit (usefulness) than the number of members (direct network externalities). This finding suggests that the individual strongly believes that the breadth of his friends using SNS is great (Baker & White, 2010) or when complementary resources such as various supporting tools, applications, and groups of social connections are diverse (Lin & Bhattacherjee, 2008), the degree of SNS usefulness is naturally higher (e.g., broader circle of friends and more interactions). Similarly, the number of peers and perceived complementarity predict intrinsic benefit (enjoyment), suggesting that with increased peer connections and complementary tools, SNS interaction becomes more interesting. However, another index, the number of members, has no significant effect on enjoyment; this might be because SNS builds individual-centered networks and forms self-centered groups (Boyd & Ellison, 2008), where, despite a critical legion of users, it is difficult to arouse an enjoyable mood in a user if he lacks development and connection with others. Hence, SNS service providers can enhance interactions and exchanges between people with the same interests by sponsoring activities for jazzing up and further arousing user pleasure and fun, to intensify continued intention to use.