Abstract The number of involuntary part-time workers in Israel's labor force increased by over 700% during the years 1979–1999, while the number of full-time workers (and the size of the labor force) increased by less than 100% during this period. The paper aims at understanding this rise. Our analyses, using Labor Force Surveys for 1979, 1989 and 1999 as well as annual published labor force statistics, suggest that the increase in unemployment during the period is responsible for part of the rise in the proportion of involuntary part-time workers, but it cannot explain the entire rise. The growth in involuntary part-time employment is primarily due to workers’ (especially women) shifting preferences from part-time to full-time work. The decrease in women's desire for part-time (versus full-time) work is observed among all groups of women 25–64 years old, and is unrelated to changes in the demographic composition of the labor force. The decline in women's propensity to take part-time jobs was exacerbated by employers offering a higher rate of part-time jobs in 1989 than in 1979. In the 1990s, when the total rate of part-time employment hardly changed, the decline in the propensity of women to work part-time voluntarily, “forced” employers to hire more involuntary part-time workers in 1999 than in 1989, in order to keep constant the total proportion of part-time workers.