We investigate the potential of monetary transfers across ethnic lines to mitigate ethnic-based prejudice and discrimination in a post-war context. In partnership with a local NGO, we conducted a field experiment in Liberia, a country with pronounced ethnic tensions following a prolonged civil war. Participants were randomly assigned to receive monetary transfers from donors whose ethnicity was revealed as either co-ethnic or non-coethnic. Our findings reveal that recipients exhibited a significant reduction in prejudice and discrimination toward other ethnic groups when the funds were received from non-coethnic donors compared to co-ethnic donors. Remarkably, this reduction persisted even one year after the monetary transfer. We also observed that recipients of funds from non-coethnic donors anticipated more cooperative behavior from outgroup members, suggesting that changes in perceptions of outgroup cooperativeness are the underlying mechanism driving these effects. Our study demonstrates that interpersonal monetary transfers can serve as a powerful tool to break cycles of distrust and foster intergroup cooperation in post-conflict settings.