We study the role of endogenous trust in amplifying ideological bias. Agents in our model seek to learn a sequence of states using information from sources whose accuracy is ex ante uncertain. Agents rely on noisy feedback about the state from direct experience to learn the accuracy of sources. Small biases in this feedback can cause large ideological differences in the agents’ trust in information sources and their beliefs about the states, and may lead agents to become overconfident in their own judgment. Disagreements can be similar in magnitude whether agents see only ideologically aligned sources or see a diverse range of sources.