© 2018 National Kidney Foundation, Inc. Background: Many studies have focused on the association between a single blood pressure (BP) measurement and risk for adverse outcomes. However, the association of BP trajectories during young adulthood with subsequent decline in kidney function has not been well defined. Study Design: Observational cohort study. Setting & Participants: 3,429 participants in the Coronary Artery Risk Development in Young Adulthood (CARDIA) Study enrolled between the ages of 18 and 30 years. Predictors: BP slope during the first 10 years of participation in CARDIA, derived from linear mixed models incorporating all repeated BP measures. Outcome: Decline in estimated glomerular filtration rate (eGFR) during the interval between years 10 and 20 of CARDIA participation using cystatin C measured at years 10, 15, and 20. Results: Mean age of CARDIA participants at year 0 was 25.1 years, 56% were women, and 53% were white. Every 10–mm Hg higher level of systolic (SBP) and diastolic BP (DBP) in year 10 was associated with change in eGFR of −0.09 (95% CI, −0.13 to −0.06) and −0.07 (95% CI, −0.12 to −0.03) mL/min/1.73 m2 per year, respectively. Every 10–mm Hg increase in SBP slope between years 0 and 10 was associated with a subsequent −0.52 (95% CI, −1.02 to −0.03) mL/min/1.73 m2 per year change in kidney function after adjustment for comorbid conditions and SBP at year 10. Similarly, every 10–mm Hg increase in DBP slope between years 0 and 10 was associated with a subsequent change in kidney function of −0.65 (95% CI, −1.23 to −0.07) mL/min/1.73 m2 per year, after adjustment for comorbid conditions and DBP in year 10. Limitations: Observational design. Conclusions: During young adulthood, increasing SBP and DBP are associated with a higher rate of subsequent kidney function decline, independent of BP measured at the beginning of eGFR assessment.