In 1970, Richard Rose and Derek Urwin published a seminal piece on the stability of party support in Western democracies, ‘Persistence and Change in Western Party Systems Since 1945’. Everywhere they looked, established parties seemed to reflect stability rather than change, lending credence to the notion that party systems were ‘frozen’. Numerous subsequent studies, however, have produced mixed results. Part of what seems to be fueling this debate lies in the disparate measures researchers use to gauge stability. In this update of Rose and Urwin's study, I address the issue of comparable results by maintaining the same data source and methods they used to gauge the stability of party support, extending the study to the present. The results indicate that party system instability is on the rise throughout much of the West since 1970, with statistically significant increases seen in Scandinavia and across all regions combined. Furthermore, the parties which seem to be experiencing the most change are not only the newest parties – as the frozen cleavages thesis might predict – but also those parties formed during the interwar period, the large majority of which showed much greater stability in 1970.