The social identity model of collective action (SIMCA) is frequently used to explain collection action. This study conceptualized group identification as identification with militant protestors and tested two versions of the SIMCA model with cross-sectional data collected toward the end of the anti-extradition bill movement in Hong Kong. The first model incorporates democratic ideology as the mediator and hypothesizes that instrumental, emotional, and ideological paths explain the effect of identification with militant protestors on objectively measured collective action. The second model sets democratic ideology as the antecedent and describes a process whereby a democratic ideology independently and directly influences the same three paths and thus the collective action or else influences the collective action by developing identification with the militant protestors. The results support the validity of both these models, while the model-data fitness is slightly better, and a slightly higher variance of collective action is explained with the second model. Copyright © 2021 The Society for the Psychological Study of Social Issues.