Can mood states influence the perceived truth of ambiguous or novel information? This study predicted and found that mood can significantly influence people’s reliance on processing fluency when making truth judgments. Fluent information was more likely to be judged as true (the truth effect), and consistent with Bless and Fiedler’s (2006) assimilative vs. accommodative processing model, negative mood eliminated, and positive mood maintained people’s reliance on processing fluency as an indication of truth. Post hoc analyses confirmed the predicted mood-induced differences in processing style, as judges in a negative mood adopted more accommodative processing and paid greater attention to external stimulus information. The relevance of these results to contemporary affect-cognition theories is discussed, and the real-life implications of mood effects on truth judgments in applied areas are considered.