ABSTRACT Since its inception in 2001, the CRIC Study has recruited and followed a racially and ethnically diverse cohort of 5,625 participants with reduced kidney function from 13 recruitment sites at 7 Clinical Centers across the US. The original aim of CRIC was to establish a clinical research laboratory designed to (a) identify novel predictors of CKD progression, and (b) characterize the manifestations of cardiovascular disease and identify its risk factors among individuals with CKD. As the landmark prospective cohort study of CKD, the CRIC Study has accomplished extensive biological, physiological, and social phenotyping, longitudinal follow-up, and ascertainment of clinical and patient-centered outcomes across multiple domains. Findings from the CRIC Study have defined trajectories of CKD progression, catalogued development, and evolution of comorbidities in CKD, and identified a diverse array of factors and pathways that explain the progression and complications of CKD in adults. Through its highly productive Ancillary Studies and Opportunity Pool Programs, both the scientific scope of the CRIC Study and the community of kidney disease researchers have been markedly expanded. During the most recent funding cycle (Phase 4: 2018-2023), three innovative sub-protocol studies were implemented to enrich CRIC data with highly granular home-based assessments of kidney function and cardiovascular measures. During the fifth and final phase of the CRIC Study, the major focus will be to (1) ascertain the 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, and (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. The proposed activities will generate new scientific output and successfully transition the CRIC Study from its active prospective cohort phase to a long-lasting resource for supporting ongoing and future mechanistic, epidemiologic, and translational investigations.