This article deals with the puzzle of the well-known gap between actual and preferred working hours (i.e. over-employment). We propose a new explanation based on selective attention in decision making and test it with the Time Competition Survey 2003 which includes information of I I 14 employees in 30 Dutch organizations. We find very limited support for the hypotheses that over-employment is caused by restrictions imposed by the employer (traditional lumpiness). Instead, we find much empirical support for our hypothesis on a new form of lumpiness that is related to selective attention and is created by work characteristics of ‘post-Fordist’ job design. In this work organization, the increased autonomy of workers is leading to an autonomy paradox. We also find evidence of a part-time illusion: under the post-Fordist regime, many part-time employees, who obviously were willing and allowed to reduce their working hours, still end up working more hours than they prefer.