In 1976, Jo Freeman wrote an article for Ms. Magazine, entitled ‘Trashing: The Dark Side of Sisterhood’. It provoked an outpouring of letters from women relating their own experiences of trashing during the course of the second wave feminist movement—more letters than Ms. had received about any previous article. Since then, the technology has improved but the climate among feminists has not; trashing is now conducted on social media platforms like Twitter and Facebook, in front of ever-larger audiences and with the magnified opportunities for destruction that these new platforms bring with them. Women already experience disproportionate harassment on social media; many feel trashing by other feminists to be much harder to accept. It’s one thing for people to hate feminists; resistance from those for whom a social justice movement represents a threat is par for the course. But it’s something else for feminists to hate each other. These are people with shared goals and a common enemy. What are the psychological mechanisms underlying this fact of life for feminist activists? Various explanations might be offered, from internalised misogyny, through volatility caused by histories of oppression, through envy and competitiveness, through ideological purity policing. Which are correct? Is the hatred that motivates trashing within feminism the same in quality and quantity, or different, from the affective dynamics inside other social movements? How does tribalism between warring feminist factions contribute to these dynamics, and to what extent is trashing underwritten by laudable moral goals (such as anti-elitism and anti-hierarchy) even when it goes too far or misfires? Can a liberation movement be successful without ideological purity policing, or is there a tension between achieving social justice outcomes and facilitating a healthy amount of disagreement and constructive criticism within a group? In this paper I’ll focus on potential explanations of the phenomena of trashing, including tribalism, power grabs, and purity policing; and the moral commitments that might lead feminists to trash each other.