Although research has found that people often use Facebook to present their ideal image, it is not clear whether Facebook can bring out the best self of its users. The present research investigated whether Facebook would help its users feel their best and have higher self-esteem through affirmation of the ideal self on Facebook. In particular, such Facebook affirmation might be most beneficial among moderate users. Using a correlational research design, 330 Thai participants (aged 18-35 years) were recruited through Facebook advertisements and asked to complete a set of online questionnaires. Using a moderated mediation analysis, results showed that Facebook affirmation had a positive effect on self-esteem (beta =.14, p <.05). Such an effect was partially mediated by actual and ideal-self congruence (beta =.02, p <.05). In addition, time spent on Facebook moderated both direct and indirect effects of Facebook affirmation on self-esteem. The direct effect of Facebook affirmation was more pronounced among moderate users (beta =.24, p <.05) than heavy users (beta =.02, ns). Moreover, the indirect effect of Facebook affirmation was more pronounced among moderate users (beta =.04, p <.05) than light users (beta = -. 00, ns). These results supported hypotheses that users who experienced Facebook affirmation reported having increased levels of self-esteem as a result of experiencing actual and ideal-self congruence. Specifically, moderate users benefited mostly from using Facebook, compared with light and heavy users. Key findings from this study could contribute to literature on social media behavior and the benefits from using Facebook.