This Notice of Funding Opportunity (NOFO) supports applications to develop and implement a Clinical Coordinating Center (CCC) for investigator-initiated multi-site clinical trials including efficacy, comparative effectiveness, pragmatic and/or implementation research clinical trials. Trials for which this NOFO applies must be relevant to the research mission of the NHLBI and meet the NIH definition of a clinical trial (see NOT-OD-15-015). For additional information about the mission, strategic vision, and research priorities of the NHLBI, applicants are encouraged to consult the NHLBI website.This NOFO will utilize a bi-phasic, milestone-driven cooperative agreement mechanism of award and runs in parallel with a companion NOFO that encourages applications for a collaborating Data Coordinating Center (PAR-22-193). The objective of the CCC application is to present the scientific rationale for the clinical trial and a comprehensive scientific and operational plan that describes it. The application should address project management, subject recruitment and retention, performance milestones, scientific conduct of the trial, and dissemination of results. Both a CCC application and a collaborating Data Coordinating Center (DCC) application must be submitted on the same application due date for consideration by NHLBI. Applicants are strongly encouraged to contact the appropriate Scientific/Research contact prior to submitting an application.