This thesis aims to investigate how Macau Facebook users use Facebook to construct their self-identities. An online survey of 205 Macau Facebook users was conducted to collect data. The study finds that Facebook users construct their online identities using three means: self-disclosure, photo management, and observations of other Facebook users. It also finds that Macau Facebook users are usually more confident online, are skeptical about revealing themselves online and are aware of the potential danger of disclosing personal information online. Macau Facebook users prioritize their observations of other users’ updated feeds over self-presentations on Facebook. Friend requests from strangers, bosses and superiors are usually rejected. In addition, gender and age influence online identity building. Respondents with lower education levels tend to rely on Facebook to obtain a higher level of social acceptance. Users admit to editing and providing particular data on their profiles, but they disagree that they seek to construct an ideal self or a better self through their profiles. We conclude that the self in an online community is a “confident self”, which is seemingly an appropriate way to describe those who create a different identity to obtain social acceptance in an online environment. Key Words: Social network site, Facebook, Profile, Self- disclosure, Self- presentation, Social acceptance, Self- identity, Macau.