Abstract. Individual voters' identification with a political party is believed to be a highly stable core of the political personality, and an 'unmoved mover' of political behaviour. In this article, the authors take advantage of a unique longitudinal database – the German Socio-Economic Panel (GSOEP) – to test the basic premise of partisanship's high persistence. Analysing individual-level data from 18 annual panel waves conducted in West Germany between 1984 and 2001, it was found that only a minority of the electorate appears steadfast with regard to partisanship over the entire period. Using event history analysis, the authors demonstrate how movements from partisanship into independence and changes between parties are affected by: personal attributes of voters, especially cognitive mobilisation; by properties of their social contexts, in particular spousal relationships and family constellations; by situational contexts, specifically election campaigns; and by the type of party with which voters identify.