The Chronic Kidney Disease in Children (CKiD) Study is a multi-center, cohort study of children aged 6 months to 16 years with mild to moderate impaired kidney function. Two clinical coordinating centers (CCCs) (at Children's Hospital of Philadelphia and at Children's Mercy Hospital) and a data coordinating center (at Johns Hopkins Bloomberg School of Public Health) have formed a cooperative agreement to conduct a prospective study of chronic kidney disease in children. From 2003 to 2018, we have established links with the central biochemistry laboratory (CBL) at the University of Rochester which will be maintained were they to be selected for the 2018-2023 cycle, but infastructure is in place to work with whichever institution is selected. Since its inception in 2003, the scientific aims of CKiD have been to determine the risk factors for decline in kidney function and to define how progressive decline in kidney function impacts biomarkers of risk factors for cardiovascular disease; neurocognitive function and behavior; and growth failure and its associated morbidity. The purpose of this application is to request funds to continue the cohort study from August 2018 to July 2023. The substantive scientific aims are described in the application from the collaborating CCCs. This application describes the role that the Kidney Disease in Children Data Management and Analysis Center (KIDMAC) will perform as the data coordinating center of the study. We will continue to provide leadership in study design, coordination and conduct, data management and analytical methodology and thereby enhance the scientific scope of CKiD. The specific aims of KIDMAC are: 1) to provide biostatistical and epidemiological study design expertise including methods to extend follow-up after renal replacement therapy and to introduce noninvasive devices to gather data remotely; 2) to provide the Steering Committee, the two CCCs, the CBL and the scientific subcommittees with an infrastructure to coordinate and conduct CKiD research activities; 3) to maintain and enhance the KIDMAC-developed web-based system to manage the data of CKiD; 4) to provide biostatistical and epidemiological leadership in the analysis, interpretation and presentation of study-wide initiatives including the development of methods for the appropriate analyses of the CKiD data (e.g., usage of time since CKD diagnosis as time scale for analysis, joint survival and longitudinal data analysis, and methods for causal inferences); and 5) to implement a quality assurance program that integrates expertise in data management, study coordination, statistical methodology and scientific disciplines. KIDMAC investigators have expertise in research design, coordination, data management, quality assurance and epidemiological and biostatistical methods for complex longitudinal and survival data.