||As one of the most destructive socio-political upheavals in the history of contemporary China, the Cultural Revolution (1966-1976) incentivized people to snitch on each other to signal loyalty to the Party. This paper identies the causal eect of exposure to Cultural Revolution on social trust, taking advantage of both cohort and regional variation. Specically, the regional intensity variation is captured by the number of abnormal deaths on county level, and cohort variation is measured by the interrupted years of schooling during the Cultural Revolution. The major nding is that individuals from counties with higher Cultural Revolution intensity and exposed to more years of interrupted schooling during the revolutionary years signicantly trustless. I also discuss mechanisms through which the Cultural Revolution aected social trust. Robustness checks are conducted considering migration issues, measurement error, omitted variable bias, heterogeneous eects and placebo test.