["Political Psychology, EarlyView. ", "\nAbstract\nDespite mass mobilization efforts, most countries are failing to meet their internationally agreed 2030 goals to mitigate climate change, representing a failure of the climate movement to achieve their key aspirations. Most research on failure and collective action examines one‐off failures but does not address lasting failure. We conceptualize this ongoing failure as collective gridlock: times in social change advocacy where insufficient progress is caused by antagonistic intergroup stalemates, preventing groups from achieving shared goals and addressing joint problems. We used semi‐structured interviews with climate movement leaders (N = 28) to explore collective gridlock and the processes that may be associated with it. Most advocates believed they were in gridlock as they perceived insufficient progress toward their movement's goals. Evidence for the proposed processes of attrition, group norms of purity and intransigence, moral conviction, hostility toward the outgroup, radicalization, and perceived counter‐mobilization emerged in the interviews. Contrary to expectations, climate movement leaders also reported a need to build coalitions and compromise, and they also discussed negative well‐being as an outcome of collective gridlock. The current study contributes to our understanding of persistent failure in the climate movement and its implications for social change advocacy.\n"]