In Aotearoa New Zealand stark social class inequities persist between Maori (Indigenous) and Pacific people and the Pakeha (New Zealand European) majority. These inequities are apparent in domains including education, income, health, and incarceration. The article explores the relationship between streaming (tracking) and historically rooted ethnic inequalities in one diverse urban setting. Drawing survey, assessment, and administrative data from 450 eighth-grade students across three multicultural secondary schools, we ask how school mathematics reinforces or disrupts social-class divisions between majority Pakeha and minoritized Maori and Pacific students. Students entering secondary school imagined their future careers in ways that were already strongly differentiated by race, class, and gender. Tracking students into racially stratified mathematics classes reinforced such inequalities through a self-reinforcing interaction between aspirations and mathematics achievement.