Despite persistent gender differences in field-of-study choices, existing research has not exhaustively explained why men and women continue to opt for different fields of study. This study aims to address this question by combining different explanatory frameworks and exploring the gender gap in five different fields of study. Utilizing multinomial regression and decomposition analyses, our results show that gender differences in field-of-study choices are mainly attributable to the student’s previous educational biography, self-assessment of performance, and occupational interests. These, in turn, are strongly interrelated. Thus, cultural notions of masculinity and femininity do not seem to manifest themselves in anticipated discrimination in gender atypical fields, but rather in the development of gender-specific ability and interest profiles. However, the results also reveal that mechanisms contributing to the gender gap differ somewhat across fields of study.