Populism is usually studied by looking at the electoral and rhetorical strategies of parties considered to be populist. In contrast, this article attempts to measure the support for the core propositions of populism among voters and explain the social differences in that support. On the basis of a survey of the Dutch-speaking population of Belgium (N: 2,330) we find that this support for populism turns out not to be directly influenced by a weak or uncertain economic position, by dissatisfaction with personal life or feelings of anomie. Support for populism appears foremost as a consequence of a very negative view of the evolution of society – declinism – and of the feeling of belonging to a group of people that is unfairly treated by society.