PROJECT SUMMARY This application is submitted in response to RFA-DK-22-502, “Limited Competition for the Continuation of the Chronic Renal Insufficiency Cohort (CRIC) Clinical Centers (U01),” aka Phase 5 of CRIC, for the Hopkins/University of Maryland (Hopkins/UMB) Clinical Center. Since its inception, CRIC has recruited and followed a racially and ethnically diverse cohort of 5,625 participants with reduced kidney function at 7 Clinical Centers across the US. As the landmark cohort study of CKD, it has accomplished extensive biological, physiological, and social phenotyping, longitudinal follow-up, and ascertainment of clinical and patient-centered outcomes across multiple domains. In the process, it has made major scientific contributions. In Phase 5, CRIC will have the following aims: 1) ascertain clinical outcomes for all participants including those enrolled in the Phase 4 sub- protocols, 2) perform analyses linking the sub-protocol measurements to clinical outcomes, 3) integrate data from multiple domains to identify sub-phenotypes underlying the heterogeneity in CKD progression outcomes, 4) conduct final study visits for the full CRIC cohort eligible for Phase 5, 5) create mechanisms for future data collection via linkages with external sources of health data, 6) generate tools and resources to facilitate ongoing use of CRIC data and biospecimens by a broad group of investigators after the CRIC Study has officially ended. Leveraging its vast expertise in the design, conduct, and dissemination of high quality observational research, the investigative team at Hopkins/UMB contributed substantively to scientific and operational aspects of CRIC, and ultimately its success. During Phases 1-4 of CRIC, the Hopkins/UMB Clinical Center was a high performing center that exceeded its recruitment goals during the Phase 1 and 3 recruitment drives; achieved high re-enrollment and follow-up rates in Phases 2-4; collected high quality data; implemented the Phase 4 subprotocols; and contributed substantially to the productivity of the study. Likewise, center investigators and senior staff have consistently had prominent leadership roles (e.g. Co-Chairs of Recruitment/Retention, Ancillary Studies, and Publications Subcommittees). In Phase 5, the Hopkins/UMB team is extremely well-positioned to implement the Phase 5 protocol and contribute substantively as CRIC transitions from an active cohort study to a long-lasting resource that supports ongoing and future mechanistic, epidemiologic, and translational investigations.