Gender segregation in fields of study represents an important explanation for gender inequalities in the labor market, such as the gender wage gap. Research shows that horizontal gender segregation in higher education persists for a variety of reasons, including women's greater communal goals and men's greater motivation to earn high incomes. Yet with the male breadwinner model in decline, a key question is whether women's motivation to earn high incomes might contribute to increasing women's participation in female-atypical fields of study. Using data from the German Student Survey over a period of 30 years, our findings show that the proportion of women enrolled in female-atypical fields of study increased from 1984 to 2015. Moreover, women's motivation to earn high incomes mediates the effect of time on enrollment in female-atypical fields of study. Their motivation to earn high incomes might thus be a factor contributing to the disruption of gender segregation in fields of study over time. Furthermore, contrary to expectations, the motivation to earn high incomes as a driving force for women to opt for gender-atypical fields of study is not stratified by social background.