We use two administrative data sets to examine the correlates of (a) taking the high school courses needed for university science, technology, engineering, and mathematics (STEM) programs and (b) applying to and registering in such programs. Staying on the STEM path during high school depends most importantly on math and science grades at each level. Factors such as gender, immigration status, and average neighbourhood income play relatively smaller roles. These two sets of factors play similar roles in the transition to university STEM programs. These results raise challenging questions of what lies behind the differences in critical factors among high school students.