AbstractIt is essential to understand the psychological mechanisms that help explain how people perceive, and why they participate in, social movements. Two psychological theories relevant to this endeavor are founder ownership and system justification beliefs. The current work examined how founder ownership and system‐justifying beliefs related to people's attitudes toward the Black Lives Matter movement (Studies 1 and 2) and other social movements (Study 2), as well as people's willingness to participate in collective action for these movements (Study 2). Across two studies, participants (total N = 1064) completed measures of founder ownership beliefs, system justifying beliefs, general political orientation, and attitudes and participation intentions toward different social movements. We found that, even after controlling for demographics, people higher in founder ownership and system justifying beliefs still held more negative attitudes toward social movements that challenged the status quo and were less willing to engage in collective action that supported these movements. The present findings highlight some important psychological processes that help explain why some people are more or less likely to support and engage in social change.