This article analyzes the process through which partisan bias arises during the formation of citizens' judgments of political responsibility. Informed by theories of motivated political reasoning, it argues that exposure to partisan cues motivates partisans to pursue directional goals, goals which bias the cognitive processing of information and, in turn, overall judgments of responsibility. It further argues that the nature of this biased processing will be such that partisans devalue information inconsistent with their partisan affect. Using a pair of experiments, I test these hypotheses by manipulating both objective evidence concerning gubernatorial responsibility for a state's fiscal imbalance and the presence of partisan cues. Findings support both sets of expectations. The results also suggest that the effects of partisan bias are greater in judgments tied to institutional actions than in those tied to institutional roles and expectations.