Most German states have recently reduced the duration of university preparatory schooling from 13 to 12 years without changing the graduation requirements. We use nationwide data on high school graduates and the different timing of reform introduction in the federal states to identify the effects on postsecondary education decisions and to evaluate potential effect mechanisms. The results show that university enrollment of female students decreased in the first year after graduation in all analyzed states, whereas participation in voluntary service or staying abroad increased. Furthermore, students from non-academic families are more affected than students from an academic family background.