In this study, I propose a more differentiated conceptualization of party novelty that shifts from the age of party, and viewing newness in terms of organizational youthfulness (how close to birth, how far removed from death), to something more complex, i.e. the ‘newness’ of party leaders, programmes, names, etc. Thus, this concept supplements the understanding of novelty in strictly organizational terms proposing to consider also other elements. I call it a ‘thick’ conceptualization of party novelty. I argue that, in a given electoral cycle, any party is new to some degree. I propose to measure party novelty considering changes of party attributes and changes of party structural affiliation. I present the Party Novelty Database, which records changes in national parties participating in the EU parliamentary elections from 1989 to 2009. I show that party novelty exists and varies. In more than 80 percent of cases, parties changed themselves in various ways and to varying degree, with Italy and France showing the highest levels of novelty and Finland and Sweden the lowest over the period considered. In conclusion, I suggest the ways in which the concept and the measure of party novelty can be used to explain political phenomena.