Building upon the theories of nested identity and optimal distinctiveness, this study examines the identity structure of Hong Kong Twitter users as reflected in their tweets and how their structure changed over time during the Anti-Extradition Movement. By employing semantic network analysis and discursive historical analysis, we found that the identity structure expressed by Hong Kong Twitter users manifested a composite mesh of a sense of victimization, democratic values, sense of autonomy, and sense of helplessness. Moreover, the way Hong Kong Twitter users distinguished themselves from others was hybrid and miscible, justified by an affirmation for morality. The identity expression changed its emphasis regarding different identity concepts as the movement evolved. Implications on how social movement impacts identity politics, and vice versa, are also discussed. [ABSTRACT FROM AUTHOR]