Underrepresented racial minority college students attending predominantly White institutions disproportionately experience school-based racial/ethnic microaggressions, which can impede college satisfaction and college graduation rates. This study examines the longitudinal implications of school-based racial/ethnic microaggressions on college attitudes (e.g., college satisfaction and graduation expectations). The study also compares the mediating roles of academic achievement (GPA) and academic affect (feelings toward academic experiences). Among a sample of 437 Black and Latinx college students attending five universities in the Midwestern United States, results indicated that academic affect, but not academic achievement, mediated the relationship between school-based microaggressions and graduation expectations. Additionally, school-based discrimination indirectly predicted lower college satisfaction through a negative impact on academic affect. Overall, more frequent exposure to school-based discrimination in college led to lower academic affect, which in turn, predicted lower graduation expectations and lower college satisfaction. These findings highlight the powerful role of academic affect in explaining how racial discrimination impairs graduation expectations and college satisfaction over time. Implications and policy recommendations regarding the impact of racial discrimination on underrepresented minority college students are further discussed.