Scholars assume that citizens perform better when they know pertinent facts. Factual beliefs, however, become relevant for political judgments only when people interpret them. Interpretations provide opportunities for partisans to rationalize their existing opinions. Using panel studies, we examine whether and how partisans updated factual beliefs, interpretations of beliefs, and opinions about the handling of the Iraq war as real-world conditions changed. Most respondents held similar, fairly accurate beliefs about facts. But interpretations varied across partisan groups in predictable ways. In turn, interpretations, not beliefs, drove opinions. Perversely, the better informed more effectively used interpretations to buttress their existing partisan views.