Objective: To examine prospective relations of perceived racial discrimination at ages 16–18 with body mass index (BMI) at ages 19–21 and insulin resistance (IR) at ages 25 and 27 among Black youth in the rural South, and to determine whether BMI connected discrimination to IR as a mediator. Method: Participants were 315 African American adolescents in rural counties in Georgia who provided data on their perceptions of discrimination during adolescence. BMI was measured during a yearly home visit, and a certified phlebotomist drew a fasting blood sample from which IR was measured. Results: The data analysis, with all confounding variables controlled, revealed that, over time, (a) discrimination was associated positively with both BMI and IR; (b) BMI was associated positively with IR; and (c) BMI acted as a mediator connecting discrimination with IR. Conclusions: The findings are consistent with the hypothesis that exposure to discrimination presages IR through its effects on BMI. (PsycINFO Database Record (c) 2018 APA, all rights reserved)