Team Populism brings together renowned scholars from Europe and the Americas to study the causes of populism. We seek to answer why some populist parties, leaders or movements are more successful than others. Our general argument is that populism is best understood as a combination of individual and contextual issues (“demand side") and the availability of successful leaders (“supply side"). We expand on this broad framework by studying multiple levels of analysis, and we draw on different methodological tools, including experiments, surveys, and comparative analysis. To facilitate this work, individual teams are organized around functional tasks.