This study investigates how the presence of a radical flank in a social movement affects public support for moderate and radical activists. Two experimental studies were conducted, examining reactions to protests in the UK and the US. Participants read fictional newspaper articles about movements with either nonviolent, violent, or mixed tactics. The results showed that the presence of a radical flank increased public support for moderate activists and decreased support for radical activists. In Study 1, the moderate group received more support, while in Study 2, the radical group lost support. The effects were moderated by participants' sympathy for the movement's cause. Sympathetic observers reacted more strongly to the tactics used by the activists. The study highlights the complex role of radical flanks in social movements, showing that they can influence public perception and support through contrast effects. The findings suggest that activists may benefit from strategically positioning their group within the movement to gain public support. The study also emphasizes the importance of understanding the context and the audience's perspective when evaluating the impact of radical tactics on public support.This study investigates how the presence of a radical flank in a social movement affects public support for moderate and radical activists. Two experimental studies were conducted, examining reactions to protests in the UK and the US. Participants read fictional newspaper articles about movements with either nonviolent, violent, or mixed tactics. The results showed that the presence of a radical flank increased public support for moderate activists and decreased support for radical activists. In Study 1, the moderate group received more support, while in Study 2, the radical group lost support. The effects were moderated by participants' sympathy for the movement's cause. Sympathetic observers reacted more strongly to the tactics used by the activists. The study highlights the complex role of radical flanks in social movements, showing that they can influence public perception and support through contrast effects. The findings suggest that activists may benefit from strategically positioning their group within the movement to gain public support. The study also emphasizes the importance of understanding the context and the audience's perspective when evaluating the impact of radical tactics on public support.