This Article analyzes Pope Francis’ 2015 environmental encyclical, “Laudato Si’,” as a form of private environmental governance. Focusing on the effects of the encyclical, this Article explores efforts to disseminate and implement the encyclical, its effects on public views regarding climate change and other environmental issues, and its invocation in policy debates. The encyclical relates to formal law in several ways: it can inform the law, it can raise (or lower) support for new laws, it can function as soft law and become a foundation for hard law, and it can motivate extra-legal efforts that complement the law while operating independently of it. This Article explores these various modes of influence and compares the efforts of the...