This paper investigates the impact of tertiary education expansion on fertility outcomes of women past the usual college-entry age. We show that the tertiary education expansion in Taiwan led to a decrease in fertility for these mature women both with and without tertiary education, suggesting that the effect did not operate through education alone. Our findings also highlight two empirical concerns with previous studies: (i) the mis-classification of women past college-entry age as “unexposed” to the expansion in the difference-in-differences studies, and (ii) the potential violation of exclusion restriction when using the expansion as an instrument for female education in the instrumental variable studies.