<p>Despite the fact that law-breaking or violent climate action tactics receive enormous media coverage, the psychological predictors of intentions to engage in these tactics remain poorly understood. This study examined demographic and psychological factors theoretically associated with conventional and radical climate intentions among 1427 self-identified supporters of climate action, tracked in three waves over 12 months. Conventional activism intentions were predicted by established models emphasising the role of moral conviction, anger, group identification, and group efficacy in shaping action. However, in the case of radical climate action, these variables were either weak predictors or non-significant predictors. Contrary to the notion that radical climate actors are driven by outgroup antipathy and ideological intensity, radical action intentions were positively associated with warmth and empathy toward climate change opponents, unrelated to political ideology, and negatively related to belief in climate change. Radical action intentions were also predicted by youth, personality, and—most strongly—the perception that people who support action on climate change have suffered more than opponents (collective victimhood). These findings suggest that theories require updating to account for the unique motivations associated with support for radical tactics in the climate change context. Findings have implications for activists and researchers seeking to understand the evolving landscape of climate protest and public support for disruptive activism.</p>