Objective: Previous research has indicated that school engagement tends to decline across high school. At the same time, sleep problems and exposure to social stressors such as ethnic/racial discrimination increase. The current study uses a biopsychosocial perspective to examine the interactive and prospective effects of sleep and discrimination on trajectories of academic performance. Method: Growth curve models were used to explore changes in 6 waves of academic outcomes in a sample of 310 ethnically and racially diverse adolescents (mean age = 14.47 years, SD = .78, and 64.1% female). Ethnic/racial discrimination was assessed at Time 1 in a single survey. Sleep quality and duration were also assessed at Time 1 with daily diary surveys. School engagement and grades were reported every 6 months for 3 years. Results: Higher self-reported sleep quality in the ninth grade was associated with higher levels of academic engagement at the start of high school. Ethnic/racial discrimination moderated the relationship between sleep quality and engagement such that adolescents reporting low levels of discrimination reported a steeper increase in engagement over time, whereas their peers reporting poor sleep quality and high levels of discrimination reported the worse engagement in the ninth grade and throughout high school. Conclusion: The combination of poor sleep quality and high levels of discrimination in ninth grade has downstream consequences for adolescent academic outcomes. This study applies the biopsychosocial model to understand the development and daily experiences of diverse adolescents.