Definition · Plain-language
Principal investigator
A principal investigator (PI) is the researcher with primary responsibility for the design, conduct and management of a funded research project.
The step most authors miss
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What the PI is responsible for
The principal investigator holds scientific and administrative responsibility for a project: designing the research, leading the team, overseeing the budget, ensuring ethical and regulatory compliance (such as human-subjects or animal-care approvals) and reporting progress to the funder. While the award is legally made to the institution, the PI is the named individual the funder holds accountable for delivering the proposed work and stewarding public funds.
Single PI and multiple PI awards
Historically each award had one PI, but NIH and other funders now support a Multiple PD/PI model in which two or more investigators share leadership and accountability under a leadership plan. This recognises team science and interdisciplinary collaboration. One PI is designated the contact PI for communication with the funder, but all named PIs share responsibility for the project’s conduct and outcomes.
PI versus other contributor roles
The PI is distinct from co-investigators, key personnel and authorship roles. Being a PI denotes accountability for the award to the funder, whereas contribution to a resulting publication is described separately — for example through the CRediT taxonomy of roles. A person can be a PI on a grant and hold any combination of CRediT roles on the papers that grant produces; the two systems describe different relationships.
Key facts
At a glance
- Definition: individual responsible for a research project/award
- NIH title: Program Director/Principal Investigator (PD/PI)
- Accountable for: science, budget, staff, compliance, reporting
- Award holder: usually the institution, not the PI personally
- Models: single PI or Multiple PD/PI with a leadership plan
- Identified by: persistent eRA Commons ID at NIH
Common misconceptions
What people often get wrong
Often heard: The PI personally owns the grant money.
Actually: The award is normally made to the institution, which is legally responsible for the funds; the PI directs the work but does not personally own the grant.
Often heard: A project can only ever have one PI.
Actually: Many funders, including NIH, allow Multiple PD/PI awards where two or more investigators share leadership under a formal leadership plan.
Often heard: Being PI is the same as being first author.
Actually: PI status describes accountability for a grant to a funder; authorship and contribution are described separately, for example through the CRediT taxonomy.
Going deeper
