Do discussions in echo chambers break down barriers on the acceptance political violence? We know from research within political science, social psychology and communication that deliberation in echo chambers—called enclave deliberation—works as a driver for the amplification of existing political attitudes. Moreover, scholars of radicalization have argued that enclave deliberation can lead to extremist ideas and the acceptance of political violence in response to political grievances. Yet, amplification of attitudes, even into extremist ideas, is not the same as accepting violence. We still lack causal backing for the widespread claim that enclave deliberation fuels acceptance of political violence. Utilizing a novel laboratory experiment with 188 participants, this article delivers causal evidence suggesting that enclave deliberation increases politically aggrieved group members’ acceptance of violence. In addition, I find causal evidence supporting the claim that enclave deliberation amplifies existing political attitudes and makes group members’ opinions less diverse.