abstract: Populists’ ideological opposition to global governance is well recognized, yet whether and how these actors systematically undermine international organizations remain unclear. The authors argue that a key means by which populists warp global governance is by distorting scientific information, which is necessary for global responses to many public health and environmental issues. Populists are motivated to withhold or misreport scientific information due to their anti-elite, prostate sovereignty views. Using new data on the source and quality of information provided to international organizations (ios), the authors find that populist leaders are significantly less likely to provide scientific information to ios than are other types of leaders. When they do offer such data, they are less accurate than the information that other sources supply. The authors’ findings suggest that populism may stymie international institutions’ ability to govern in areas of pressing international concern.