Due to the rise of populist parties in Europe, it is often assumed that mainstream parties also increasingly adopt populist communication. However, there is little empirical evidence in this respect. Generating a better understanding of a potential contagion effect is particularly important given the recent emergence of new actors such as Podemos in Spain, the Movimento 5 Stelle in Italy, and the Alternative für Deutschland in Germany. This PhD project aims to address this research gap by assessing the impact these new populist actors have on center-left and center-right mainstream parties regarding ‘anti-elitist’ and ‘people-centered’ communication strategies in election manifestos and official statements on party websites. Furthermore, it is investigated if mainstream parties increasingly employ ‘anti-migration’ communication as well as negative evaluations of economic actors due to the establishment of new populist parties from the far-right (AfD, Germany) and from the left (Podemos, Spain).