This paper evaluates the effects of a high school curriculum reform on students' probability to enroll at university and to choose a Science, Technology, Engineering or Mathematics (STEM) major. The reform increased the difficulty of graduating from high school by increasing the instruction time in core subjects and by raising the graduation requirements. Based on administrative data covering all students, the analysis is carried out by applying a difference-in-differences model. The results show that the reform increased university enrollment rates for both genders. With regard to choosing STEM as college major, we find a robust positive effect on males.