There is little information on how the duration of overweight or obesity during life affects the risk for CKD. To investigate whether prolonged exposure to overweight during adult life increases the risk of later CKD in a cumulative manner, we analyzed data from the Medical Research Council National Survey of Health and Development, a socially stratified sample of 5362 singleton children born in 1 week in March 1946 in England, Scotland, and Wales. Multiple imputation expanded the analysis sample from the initial 1794 participants with complete data to 4584. This study collected self-reported body mass index (BMI) at ages 20 and 26 years and measured BMI at ages 36, 43, 53, and 60-64 years. The outcome of interest was CKD at age 60-64 years, suggested by estimated GFR (eGFR) <60 ml/min per 1.73 m(2) and/or urine albumin-to-creatinine ratio (UACR) ≥ 3.5 mg/mmol. In analyses adjusted for childhood and adulthood social class, first becoming overweight at younger ages was associated with higher odds of developing CKD by age 60-64 years. Compared with those who first became overweight at age 60-64 years or never became overweight, those first overweight at age 26 or 36 years had approximately double the odds of developing CKD. The strength of this association decreased with increasing age when first overweight (P for trend <0.001). These associations were consistent for creatinine-based eGFR, cystatin C-based eGFR, and UACR. Taken together, these results suggest that preventing overweight in early adulthood may have a considerable effect on the prevalence of CKD in the population.