The middle school transition year poses known challenges to early adolescent adjustment, particularly for students from ethnic and racial minoritized backgrounds who face ethnic and racial discrimination from school personnel and classmates. Drawing on a sample of 711 African American and Latinx sixth-grade students attending 17 schools, we employed latent class analysis and latent transition analysis to explore the nature of and changes to perceived ethnic and racial discrimination during the beginning and end of sixth grade. We also examined the possibility that perceived ethnic-racial discrimination could be diminished through a school-based, universal program for teachers to improve the school ecology. Findings revealed four distinct classes concerning perceived ethnic-racial discrimination, with patterns over time highlighting the malleability of perceived ethnic-racial discrimination during the first year of middle school. Findings provide direct implications for understanding and improving ethnic and racial minoritized students' school experiences at the middle school transition.