This study employs the definition of the thin ideology of populism developed by Cas Mudde and operationalizes it as a three-part measure drawing on 'the moral people', 'the corrupt elite' and the call for the primacy of the will of the people. In a first step, the paper uses a dictionary approach to ascertain the populist content of national party manifestos of six Northern and Central European party systems between 1960 and 2017. The countries thus analysed are Sweden, Denmark, Norway, Germany, Austria and Switzerland. In a second step, I draw on the variation in parties’ populism and the emerging panel data structure to analyse the change in parties’ use of populism since 1960 in each of the six countries. In a third step, I use the populism score of each party manifesto as a dependent variable to conduct a regression analysis to scrutinise how a party’s opposition or government status, general ideology, size, time in parliament and more fine-grained stands on particular policy issues predict its use of populism.
