High school course selection can affect student outcomes in high school, college, and beyond. Policymakers therefore must consider whether policies affecting course selection may have unintended consequences for students with different levels of preparation. We use regression discontinuity analysis to examine the impact of Florida's College and Career Readiness Initiative on high school coursetaking and subsequent success in college-level courses. To determine which students were most likely to comply with and benefit from the FCCRI, we run subgroup analyses based on students' course-taking histories, finding that the initiative was beneficial for some students but may have had inadvertently harmed others.