The present research examined the hypothesis that participation in radical, but not moderate, action results in disidentification from the broader in-group. Study 1 (N = 98) was a longitudinal study conducted in the context of student protests against tuition fees in Germany and confirmed that participation in radical collective action results in disidentification with the broader in-group (students) whereas participation in moderate collective action does not. Both types of action increased politicized identification. Study 2 (N = 175) manipulated the normativeness of different types of imagined collective actions in the same context and replicated this disidentification effect for radical actions, but only when this action mismatched the broader in-group's norms. This study also indicated that these effects were partially mediated by perceived lack of solidarity and perceived lack of commitment to the cause among the broader in-group. The implications of these findings for understanding radicalization within social movements are discussed.