PURPOSE: To assess longitudinal and geographic variation in perceived discrimination from ages 10-11 to 13-14 years in the Adolescent Brain Cognitive Development cohort, and to examine how these experiences are shaped by contextual factors such as neighborhood segregation and state-level racial bias. METHODS: Data were drawn from the longitudinal Adolescent Brain Cognitive Development Study (release 5.1), analyzing years 1, 2, and 4, corresponding to approximate ages 10-11, 11-12, and 13-14 years. Perceived discrimination was assessed using items adapted from the Perceived Discrimination Scale. Mixed-effects logistic regression models examined how perceived discrimination varied across time, demographic factors, and contextual variables, with models weighted using American Community Survey raked propensity scores to ensure national representativeness. RESULTS: Black, Asian American and Pacific Islander, and Other/Multiracial non-Hispanic youth showed increasing trajectories of perceived discrimination over time, while Native American and White non-Hispanic youth exhibited decreasing trends. Significant geographic variation emerged, with Black youth reporting elevated discrimination across all regions, particularly in the West and South. Youth living in areas with concentrated poor Black households and in states with high anti-Black bias reported higher discrimination. Youth with immigrant backgrounds generally reported higher levels of perceived discrimination across most racial/ethnic groups. DISCUSSION: Perceived discrimination follows distinct developmental trajectories during early adolescence that vary significantly by race, ethnicity, geography, and structural context. These findings highlight the critical need for targeted interventions during this developmental period, particularly for Black, Asian American and Pacific Islander, and Other/Multiracial youth. Context-specific approaches to addressing racism are essential for mitigating its harmful effects on adolescent development.