Dr. Gijs Schumacher will present a new theory proposing that party behavior is influenced by current and future electoral performance and expectations of performance formed by historical experience. Contrary to what many existing theories claim, government parties change their electoral program more than opposition parties. Dr. Schumacher will discuss several empirical cases from contemporary Europe that illustrate that particularly parties new to government – such as green, radical right and radical left parties are likely to change. This throws an interesting light on the various radical right-wing and left-wing parties that have recently entered government for the first-time in a host of European countries such as SYRIZA in Greece, The Progress Party in Norway, The Socialist People’s Party in Denmark, or maybe will do so in the future, such as PODEMOS in Spain and Front National in France. The presentation of the new theory is extended with a perspective on party organizational change and party influence on policy-making.