Plurality decisions on the Supreme Court represent extreme dissensus. In those cases, no clear majority is formed for any one controlling rationale for the final disposition. Such decisions are important to understand both because they result in the erosion of the Court’s credibility and authority as a source of legal leadership, and because they teach us broader lessons about judicial decision making. In this paper we ask: what causes the Court to issue an opinion which lacks precedential value? We propose and test three theories to explain plurality decisions - a social consensus account, a “hard” case theory, and an explanation based on the “collegial game.” Hypotheses are tested based on all orally argued cases during the 1953-2006 terms. We find that splintering is more likely when the Court reviews contentious or politically salient questions, in constitutional cases, and when the median justice writes the opinion. When the Chief Justice assigns the opinion, plurality decisions are less likely. We discuss our findings in light of existing theories of judicial decision making and examine how our new understanding of plurality opinions sheds light on decision making on the Court more generally.