I use the 1993 and 2003 National Surveys of College Graduates to examine the higher exit rate of women compared to men from science and engineering relative to other fields. I find that the higher relative exit rate is driven by engineering rather than science, and show that 60% of the gap can be explained by the relatively greater exit rate from engineering of women dissatisfied with pay and promotion opportunities. I find that family-related constraints and dissatisfaction with working conditions are only secondary factors. The relative exit rate by gender from engineering does not differ from that of other fields once women's relatively high exit rates from male fields generally are taken into account.