This may be a stupid question, but I can't quite figure it out. For an academic career, it seems to be quite important to be "principal investigator (PI)" on cool research projects. Now, say for some reason you're not eligible to be an official applicant on a grant proposal (e.g., because you're abroad and the funding agency doesn't permit that), but you're still involved as a project leader, providing important scientific stimuli, attending meetings, etc. - can you still call yourself a "PI" (as long as all involved parties agree), or is that an official stamp that really only the formal appointee of the grant receives?

To make it a bit less hypothetical: I'm thinking about writing a grant proposal with my former supervisor for funding a PhD student at his institution, with me co-leading the supervision of the student. I'm currently abroad, doing a PostDoc at another institution, and I'm trying to figure out whether there's a way I can be involved in that project and receive "official academic credit points" for it. ;-)

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    It sounds like you will be listed on the grant as supporting personnel. Nothing wrong with that, you will receive credit for the part you are taking. You cannot call yourself a PI at that point, but I think you have a misconception that anyone expects you to be a PI while you are still a postdoc.
    – Dan Romik
    Commented Sep 20, 2021 at 19:09
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    Note that PI isn't used at all, or only informally, in some fields. In pure math, for example, the one that founds a small seminar or working group might be informally refereed to in that way, but it has no real import. The work of members is largely independent other than for a sharing of ideas. They don't "direct" the work of anyone but there own advisees.
    – Buffy
    Commented Sep 20, 2021 at 19:38
  • @GoodDeeds thanks for the link! That partially answers my question, but the answers here helped to further clarify things.
    – Eike P.
    Commented Sep 20, 2021 at 20:27
  • Can you not be a co-PI either?
    – Kimball
    Commented Sep 21, 2021 at 11:24
  • 1
    This is a good question. In other words, is PI something that people are formally appointed to (or not appointed to), or is a PI simply someone who does PI-like things, self-identifies as a PI, takes a leadership role in research, etc.? Compare being a project manager (someone who manages projects) and being formally awarded the specific job title of Project Manager at a specific industry employer. Lots of people manage projects in industry while having some other formal title (e.g. Engineer, Developer, etc.). Commented Sep 21, 2021 at 16:10

3 Answers 3


There are three only partly-overlapping senses of the label "PI" that I am familiar with in the US; as usual, things may vary a bit elsewhere in the world:

  1. Shorthand for professor/advisor in a research setting. When a student refers to "my PI" they mean the person overseeing their research. It may help resolve the ambiguity of saying "my professor" which might be taken to mean "the instructor of a course I am taking".

  2. "PI status", meaning eligibility to apply for grants on behalf of an institution. For example https://research.wisc.edu/compliance-policy/principal-investigator-status/ talks about the responsibilities and eligibility to be a PI. For tenured/tenure-track faculty it's pretty much a given, though others may be eligible for the role, too.

  3. The actual bona fide "principal investigator" on a grant. This is distinct from the other uses of the term, and is totally up to the policies of the grant institution/organization. Some people may be officially a PI in this sense of the term but yet would not be called a PI in either of the other circumstances. For example, the recipient of a doctoral or post-doctoral fellowship may be officially the "principal investigator" on that grant.

For your specific situation, I think it depends on what sense you're thinking of "PI". If you're going to be someone's primary mentor, maybe they'd call you their "PI", and there's no need for you to scold them over it and demand they use a more correct title. However, if you're listing the activity on your CV it would be better to just describe the relationship rather than put any title on it. If you've mentored a graduate student, list it as a graduate student mentored/supervised. If it's a co-supervisory relationship, you may also want to make that clear. Something like "PhD Students Supervised" in a heading, and then a line like "Student A. Learner, PhD University of Important Things (co-supervised with Dr. Big S. Hot)"

If you're submitting a grant where there is some box to fill in who the PI is, well, it completely depends on the rules for that granting agency. It sounds like you don't fit those requirements, so no, you aren't a PI.

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    I've never heard of usage 1., actually. Is that field dependent?
    – Buffy
    Commented Sep 20, 2021 at 19:02
  • Which of those would be "boss of a scientific laboratory"? The one responsible for hiring people an establishing goals and objectives?
    – Buffy
    Commented Sep 20, 2021 at 19:05
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    @Buffy Possibly, it's pretty ubiquitous in mine. Maybe it's less so in a field where it's less likely that an advisor is also actually the PI of a grant that's funding their students. If I search this site for "PI" it seems like the usage is mostly #1, though the other situations often also apply, it's just not the context it's been used. I would include "boss of a scientific laboratory" in #1.
    – Bryan Krause
    Commented Sep 20, 2021 at 19:05
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    @Buffy I'm not intending to make any roundabout commentary on any particular situation, especially not one as specific as authorship, just noting the common conversational use of the term "PI" in my experience.
    – Bryan Krause
    Commented Sep 20, 2021 at 19:14
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    @Buffy Pretty common in the human sciences. Commented Sep 20, 2021 at 21:14

In the US, for federal grants, the "principal investigator" is defined by the grant, see the NSF search, e.g. here. If you aren't the PI on the grant, you are not the PI. I don't review early-career CVs, but you could conceivably run into someone who knows the grant, or just looks it up to learn more about it, and would see you are not the PI, and would wonder why you've listed yourself.

In conversation, it would probably be fine.

  • I've been on grant review boards, and the PI and any Co-Is are identified in the proposal. (other roles may not be ... although I once spiked a proposal when the role that was going to do all of the work wasn't identified, and they thought they were going to find a web developer / programmer / database person for $20k/yr. (for a rather complex project)
    – Joe
    Commented Sep 21, 2021 at 23:05

It depends where, and in which way, you want to use it.

When applying for jobs you want to list on your CV which grants you got. There, you don't want to lie. If you didn't get the grant/weren't the PI on it, don't claim so. If you were a co-applicant in some way, state this in a clear way on your CV, where your role becomes clear. Importantly, these parts of a CV often state how much money one got through those grants, so be honest here.

On the other hand, when you were a project leader for a project in some way or the other, this is something which is less regulated, and you can state more informally on your CV. However, then you shouldn't connect it to the grant money involved, but only relate it to your role in the given scientific project (design the project, guide postdocs/students, etc. etc.).

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    The official PI can, of course, write you a letter of recommendation describing your "central role" in carrying out the project.
    – Buffy
    Commented Sep 20, 2021 at 19:42

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