Kidney disease is highly prevalent worldwide and results in comorbid illnesses, premature mortality, reduced quality of life, and substantial healthcare costs. Given the vast scope of the kidney disease epidemic, including end-stage renal disease (ESRD), there remains a critical need to train scientists who can conduct high-impact research that addresses this societal health problem. Epidemiologic and clinical research offers the potential to reduce the morbidity, mortality, and societal costs associated with kidney disease and naturally complements and informs basic science research in kidney disease. This proposal is a competitive renewal application, years 21 to 25, for a NRSA to fund and expand our Kidney Disease Epidemiology and Clinical Research Training Program at Hopkins. The overarching goal of this training program is to identify and train scientists who have the potentia to become leaders in the design and conduct of epidemiologic and clinical research related to kidney disease. The Program is administered by the Department of Epidemiology and based in the Welch Center for Prevention, Epidemiology, and Clinical Research. It takes advantage of the faculty's strengths in the application of rigorous methodology to study kidney disease; their ability to design and conduct interdisciplinary, high-impact research; and their dedication to education and mentorship. The program Director (Dr. Appel), Associate Directors (Drs. Estrella, Fadrowski, and Segev), and 7 other nationally recognized kidney disease researchers serve as core faculty advisors, and another 12 faculty serve as affiliate faculty (co-advisors). An Advisory Committee of institutional leaders and accomplished researchers advise the program's leadership and monitor its progress. For the first 20 years, we have demonstrated our ability to recruit high-quality candidates and rigorously train them. Over the last 10 years, a total of 21 trainees have been supported, 4 of whom are still in training. Of the 17 graduates, 16 are pursuing academic careers, and the vast majority are researchers. The 17 graduates have published 208 papers. The NRSA funding has established Hopkins as a pre-eminent academic center for the design and conduct of clinical and epidemiologic research related to kidney disease; spawned new programs, including the CKD Prognosis Consortium and the Kidney Transplant Outcomes program; revitalized the Pediatric Nephrology fellowship; forged close collaborative relations across schools and academic units; and most importantly, produced a cadre of extremely successful young investigators who are doing innovative research at institutions across the U.S. Still, we will not rest on our laurels. With funding from this competitive renewal application, we intend to increase the size of our training program from 4 post-doctoral trainees to 8 trainees (6 post-doctoral and 2 pre-doctoral trainees) and expand our scope to include kidney transplantation.