Complementing the burgeoning literature on agenda setting on the Supreme Court of the United States, this article addresses a key question heretofore overlooked—Is the justices' choice to review a decision independent of the selection of cases for review by the litigants? We argue that the certiorari process cannot be modeled as an independent one; rather, it is inextricably linked with and essentially contingent on the behavior of litigants who bring the case to the Supreme Court. This dependence of the Court is important both at the level of theory and at the empirical level and ignoring it entails bias in the estimation process. Using an original database, which includes the universe of religion free exercise cases decided at the courts of appeals from 1968–2006, we find significant selection effects. Factors that influence decisions on certiorari are dependent on the behavior of petitioners and should be modeled as such.