Purpose This Notice of Funding Opportunity (NOFO) invites applications to enhance the pool of highly trained investigators from diverse backgrounds, including those from groups underrepresented in research areas of interest to the NHLBI. The career development will take place under the guidance of an experienced mentor in the biomedical, behavioral or clinical sciences leading to research independence. It is targeted toward individuals whose basic, clinical, and translational research interests are grounded in the advanced methods and experimental approaches needed to solve problems related to cardiovascular, pulmonary, and hematologic diseases and sleep disorders in the general and health disparities populations.This NOFO invites applications from institutions with eligible faculty members to undertake special study and supervised research under a mentor who is an accomplished investigator in the research area proposed and has experience in developing independent investigators.This NOFO is designed specifically for candidates proposing research that does not involve leading an independent clinical trial, a clinical trial feasibility study, or a separate ancillary clinical trial. Applicants to this NOFO are permitted to propose research experience in a clinical trial led by a mentor or co-mentor. Applicants proposing a clinical trial or an ancillary study to an ongoing clinical trial as lead investigator should apply to the companion NOFO (see RFA-HL-25-009).