A growing body of research identifies politically motivated reasoning as the source of persistent public conflict over policy-relevant facts. This paper (in press in Emerging Trends in Social & Behavioral Sciences) presents a basic conceptual model—the “Politically Motivated Reasoning Paradigm” (PMRP)—that summarizes the salient features of this form of information processing. The experimental design best suited for studying hypotheses relating to PMRP, it argues, measures the weight that subjects attach to one and the same piece of evidence conditional on the manipulation of its perceived significance for positions associated with competing cultural or political values. The paper also discusses various additional methodological and substantive issues, including alternative schemes for operationalizing “motivating” political predispositions; the characteristics of valid samples for examining politically motivated reasoning; the “symmetry” of this mechanism of cognition across opposing political or cultural groups; and the potential biasing impact of politically motivated reasoning on experts. The paper concludes by identifying the centrality of PMRP to the emerging science of science communication.