Three studies examined the hypothesis that system justification is negatively associated with collective protest against ingroup disadvantage. Effects of uncertainty salience, ingroup identification, and disruptive versus nondisruptive protest were also investigated. In Study 1, college students who were exposed to an uncertainty salience manipulation and who scored higher on system justification were less likely to protest against the governmental bailout of Wall Street. In Study 2, May Day protesters in Greece who were primed with a system-justifying stereotype exhibited less group-based anger and willingness to protest. In Study 3, members of a British teachers union who were primed with a "system-rejecting" mind-set exhibited decreased system justification and increased willingness to protest. The effect of system justification on nondisruptive protest was mediated by group-based anger. Across very different contexts, measures, and methods, the results reveal that, even among political activists, system justification plays a significant role in undermining willingness to protest.