This Funding Opportunity Announcement (FOA) supports applications to develop and implement investigator-initiated single site clinical trials including efficacy, comparative effectiveness, pragmatic and/or implementation research clinical trials. These trials may include ones that test different therapeutic, behavioral, and/or prevention strategies. Trials for which this FOA 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 FOA will utilize a bi-phasic, milestone-driven mechanism of award. The objective of the 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. The multiple PD/PI model is strongly encouraged but not required. Applicants are encouraged to include a PD/PI with expertise in biostatistics, clinical trial design, and coordination.