As soon as it was clear that Pope Francis's 2015 Encyclical, Laudato Si': On Care for Our Common Home, would discuss, among other issues, the moral imperative to address global climate change, U.S. scholars and research institutions rushed to collect data surrounding its release. These groups aimed to determine whether there would be a "Francis Effect," in which U.S. Conservatives (and Conservative Catholics in particular) would show greater concern about the negative effects of global climate change. Here, we first provide context by discussing the history of political polarization in the U.S. over global climate change. Then, we review the published literature and publicly available data that aimed to examine potential influences of Laudato Si' on people's climate change attitudes. Taken together, the available scholarship provides strong evidence that U.S. publics were differentially responsive to the Pope's messaging (with political Conservatives expressing less climate change concern and viewing Pope Francis as less credible), but there is correlational evidence of an overall "Francis Effect." U.S. population data collected following the encyclical's release show small, potentially temporary, increases in perceptions of papal credibility, climate change concern, and the perspective that global climate change is a moral issue.