How are research assistantships for international graduate students funded in the US?

Question

I was recently talking to a professor at a top university seeking advice for graduate school applications. The professor happened to mention that departments in the US have funding concerns when it comes to international students because they aren't eligible for government funding from agencies such as NIH or NSF. Moreover, admissions decisions are made based on whether there is funding available to support the student for atleast 5 years. I had a couple of questions on how exactly this works.

1. Can international students be paid through NIH/NSF grants (as research assistants) that are awarded to the PI or does a lab use funding from industrial sponsors or other endowments to fund them?
2. I was under the impression that theses government grants are usually good for a shorter duration (2-3 years). How can the department be certain of further funds at the time of admitting a candidate?

PS: The title of the question might be similar to some other questions but I am interested in understanding the broader mechanism of how this works instead of specific agencies that fund international students.

Answer 1

Can international students be paid through NIH/NSF grants that are awarded to the PI

Yes. International students are generally not eligible for personal federal fellowships, such as the NSF Graduate Research Fellowship Program, but they can still be paid through regular research grants awarded to the PI.

I was under the impression that theses government grants are usually good for a shorter duration (2-3 years). How can the department be certain of further funds at the time of admitting a candidate?

They can't. This is a major source of pressure for PIs in some fields; they have to secure funding for already enrolled students, as well as future students. If the PI is not able to secure funding through research grants, there may be institutional fellowships, industry funding, teaching assistantships, or other sources of funding that can be used in a pinch.

But, this is not really any different for international students vs any other students.

Answer 2

Projecting graduate student funding is always tricky, because most grants are not well-aligned with the coming and going of students. A faculty member with a healthy research program, however, can often make reasonable projections about how many students they will be able to sustain funding for, and there are alternative mechanisms like TAships that can help fill in the gaps.

As for how this applies to international students: one can generally think of graduate student funding as falling into five general buckets:

1. Fellowship funding, which is given directly to the graduate student and is typically restricted to US citizens (and maybe permanent residents too; I'm not sure about that)
2. Project funding from "pure science" agencies like NSF, which can generally be spent on any student that the faculty member desires. Most university funding is of this type.
3. Project funding on projects considered sensitive in some way (e.g., certain Department of Defense or Department of Energy projects) and which comes with a restriction to US citizens and/or permanent residents.
4. Internal funding, like TAships, which can usually be applied to any graduate student that the faculty decides to support with them.
5. Private funding, from corporations or foundations, which comes with whatever restrictions the funder might feel are consistent with its mission.