Grants for health-related research and research training projects or activities make up the largest category of funding provided by the NIH. Research project grants are awarded to institutions on behalf of a principal investigator to facilitate the pursuit of a scientific objective when the idea for the research is initiated by the investigator and the funding institute anticipates no substantial program involvement. The NIH awards research grants for terms ranging from one to five years.

Cooperative Agreements are similar to grants in that they are awarded to assist and support research and related activities. However, they differ from grants in that the awarding institute or center has substantial involvement in carrying out the project's activities. Since the terms and conditions of the award are above and beyond those required for the normal stewardship of grants, the rights, responsibilities, and authorities of the prospective awardee and the NIH institute are developed in advance. The awarding institute typically issues a specific request for applications (RFA) describing the program, functions, and activities as well as the nature of the shared responsibilities.

Contracts for health-related research require the awarding DHHS institute to be responsible for establishing plans, protocols, and detailed requirements. The awarding institute typically issues a specific request for proposals (RFP) for scientific inquiries in particular areas of research and development needed by the NIH. Contract performance is monitored closely by the NIH staff to ensure accomplishment of the research goals.