This study investigates the relationship between admission policies toupper secondary education and various forms of school segregation inNorway. Using a Difference-in-Differences (DiD) approach, we analyzewhether the transition from proximity-based school admissions toperformance-based admissions (free school choice) has led to increasedsegregation based on ethnicity, socioeconomic background, andacademic performance. The study focuses on the countiesencompassing Oslo and Bergen as case studies, with control groupsconsisting of counties that maintained geographically regulatedadmission throughout the observation period. Our findings indicatethat free school choice contributed to increased segregation in thedimension of academic ability. However, although segregation in theother dimensions has increased substantially over time, we find no clearevidence linking this trend to the school choice reforms. We discusspossible explanations and implications for education policy.