The Netherlands combines a high female employment rate with a high part-time employment rate. This is likely to be the result of (societal) preferences as the removal of institutional barriers has not led to higher working hours. We investigate the development of working hours over successive generations of women using the Dutch Labour Force Survey 1992-2005. We find evidence of a strictly increasing propensity to work part-time and a decreasing propensity to work full-time for the generations born after the early 1950s. Our results are in line with results of studies on social norms and attitudes. It seems likely that without changes in (societal) preferences part-time employment is indeed here to stay. Copyright 2010 CEIS, Fondazione Giacomo Brodolini and Blackwell Publishing Ltd.