This paper analyses gender differences in occupational choices in a setting in which observed matches are solely determined by supply-side factors: the French centralised medical residency selection mechanism. We show that men and women facing the same occupational choice set make drastically different occupational choices. Medical specialties selected by women pay less, have lower time requirements, and are less competitive. To understand these differences and estimate how much of the gender gap in specialty sorting can be explained by individual preferences for job attributes, we administer a survey to prospective medical residents just before their specialty choice. Using both a hypothetical job choice framework and stated preferences, we show that while “hard” job characteristics (earnings, time requirements) only slightly reduce the gender gap in sorting, “soft” characteristics (daily tasks, contact with patients, willingness to help others) play a larger role in reducing the gap. We also find suggestive evidence of an anticipation effect of fertility on women’s career choices. Our results suggest that individual preferences play a determinant role in explaining gender-based occupational segregation.