Across many countries, women enroll in science, technology, engineering, and math (STEM) fields less often than men. Using Taiwanese data from 2011–2018, we unpack the drivers of this gap. We find the gap in STEM enrollment largely reflects a gap in STEM applications. Conditional on applying to a STEM program, a female applicant is as or more likely to be admitted as a similar male applicant. We then turn to the gap in STEM applications and find one-third can be explained by math and science scores. We also find important differences between men and women in how test scores predict whether they apply to any STEM programs and how many they apply to. Finally, we find the gender gap in STEM applications differs widely across high schools, suggesting that educational institutions and social factors play a role in determining the number of women who pursue degrees in STEM.