This Notice of Funding Opportunity (NOFO) encourages cooperative agreement applications for investigator-initiated, multi-site, clinical trials (Phase III and beyond) to study the effects of natural products (i.e. botanicals, probiotics, and products marketed as dietary supplements) in NCCIH designated areas of high research priority. For this NOFO, natural products include promising nutritional regimens that standardize the amount of a specific naturally occurring nutritional compound (e.g., omega-3 fatty acids, anthocyanidins, or polyphenols) and have compelling preliminary evidence. Applicants should describe plans for a Clinical Coordinating Center to develop and implement the proposed multi-site clinical trial. The objective of the Clinical Coordinating Center application is to provide the scientific rationale and a comprehensive scientific and operational plan for the clinical trial. Clinical Coordinating Center applications are expected to describe plans for project management, participant recruitment and retention strategies, performance milestones, scientific conduct, and dissemination of results. Clinical Coordinating Center applications submitted under this NOFO will utilize a two-phase, milestone-driven, cooperative agreement (UG3/UH3) funding mechanism.In addition, an accompanying Data Coordinating Center application, submitted under PAR-20-219, proposing a data analysis and data management plan for the clinical project is required. Both a Clinical Coordinating Center application and a corresponding Data Coordinating Center (DCC) application need to be submitted simultaneously for consideration by NCCIH. For additional information about the mission, strategic vision, and research priorities of the NCCIH, applicants are encouraged to consult the NCCIH website: (https://nccih.nih.gov/about/plans).