The U.S. National Science Foundation does not run a single “NSF Postdoctoral Fellowship” — it funds individually held postdoctoral fellowships through a set of separately named, directorate-run competitions, each with its own solicitation and deadline. Going into the second half of 2026, that set of programs looks different than it did a year or two ago: some directorate competitions are running on schedule, while at least two of the programs most associated with broadening-participation goals are currently archived or paused. This post is a practical status check for applicants and research administrators tracking which NSF postdoctoral fellowship options are actually live right now, not a definitions page — for the general structure of NSF’s postdoctoral fellowship family (PRFB, MPS-Ascend, MSPRF, SPRF, AAPF, AGS-PF, and others), see CASRAI’s NSF Postdoctoral Fellowship dictionary entry.
Postdoctoral Research Fellowships in Biology (PRFB): open
PRFB, run by NSF’s Biological Sciences Directorate, remains active. The current solicitation is NSF 26-504, with a posted deadline of September 29, 2026. NSF’s page for the current cycle also frames this round of PRFB around the intersection of artificial intelligence and biological sciences, alongside the program’s standing structure: a 24-month, individually held, portable fellowship. Applicants and sponsored-programs offices should confirm the live solicitation text directly on nsf.gov before budgeting, since NSF has revised the PRFB solicitation number across recent cycles (it was NSF 24-593 before the current 26-504 reissue).
MPS-Ascend: archived
The Mathematical and Physical Sciences Ascending Postdoctoral Research Fellowships program (MPS-Ascend, originally issued under solicitation NSF 23-501) is listed on nsf.gov as an archived funding opportunity — it is not currently accepting applications. MPS-Ascend was structured to broaden participation among groups historically underrepresented in mathematical and physical sciences fields. Researchers who previously had MPS-Ascend on a target list for mathematical/physical-sciences postdoctoral funding should check NSF’s Mathematical and Physical Sciences directorate page for whatever successor or replacement opportunity, if any, NSF lists in its place, and should not budget around MPS-Ascend reopening without confirming that directly against nsf.gov.
SBE Postdoctoral Research Fellowships (SPRF): paused
The SBE Postdoctoral Research Fellowships program — covering both the Fundamental Research track (SPRF-FR) and the Broadening Participation track (SPRF-BP) — is currently shown on nsf.gov as “waiting for new publication,” with no upcoming due dates listed as of NSF’s most recent update to that page (dated January 5, 2026). The most recent SPRF solicitation on record is NSF 23-500. NSF directs prospective applicants to contact the program office ([email protected]) for updates on when a new solicitation might be issued, rather than publishing a reopening date. As with MPS-Ascend, this means SPRF — including its broadening-participation track — is not a program applicants can currently apply to; it is paused pending a new competition announcement.
The broader policy backdrop
The status of MPS-Ascend and SPRF-BP specifically should be read against NSF’s wider 2025-2026 policy shift on broadening-participation activities. NSF’s April 18, 2025 Statement of Priorities, issued by the NSF Director, reframed how the agency’s Broader Impacts merit-review criterion treats activities targeted at underrepresented groups: NSF stated that broadening-participation and outreach activities “should not preference some groups at the expense of others” and that it will not fund proposals with impact “limited to subgroups of people based on protected class or characteristics.” Open, available-to-all framing (by geography, socioeconomic status, or institution type, for example) remains an acceptable basis for a broadening-participation activity; framing based on protected characteristics does not. That statement of priorities was issued for proposal-level Broader Impacts activities specifically, and NSF’s own postdoctoral-fellowship program pages do not attribute the MPS-Ascend archival or SPRF pause to it in so many words — but the timing and the shared broadening-participation design of both programs make this the relevant context for understanding why NSF’s postdoctoral-fellowship landscape looks different in 2026 than it did a few years earlier. Separately, NSF’s overall grantmaking has also been shaped by ongoing 2025-2026 litigation over grant terminations tied to DEI-related executive orders (including Thakur v. Trump in the Ninth Circuit and a related case before the U.S. District Court for D.C.), and by a slower award-making pace across the agency generally — research administrators tracking any individual NSF program’s status in 2026 should expect more volatility than in a typical prior year and should verify current status directly rather than relying on a program’s historical pattern.
What this means for applicants and research administrators
- Confirm program status before advising an applicant. “NSF has a postdoctoral fellowship in my field” is no longer a safe assumption for every discipline — check the specific program’s current solicitation status on nsf.gov, not just its past existence.
- Don’t assume archived means permanently gone, or that paused means reopening soon. NSF has periodically retired, renamed, and reissued postdoctoral solicitations before (PRFB’s own solicitation number has changed across recent cycles). Treat both “archived” and “waiting for new publication” as current-status snapshots to re-check close to any planning deadline, not as permanent determinations either way.
- PRFB remains the clearest currently-open option for a biology-focused applicant, under NSF 26-504 with a September 29, 2026 deadline — but confirm eligibility and budget details directly against that solicitation, since NSF postdoctoral programs vary in stipend structure, allowance amount, and term length even where they share a similar overall shape.
- Mathematical/physical-sciences and SBE-discipline applicants who would previously have targeted MPS-Ascend or SPRF should look for alternative NSF mechanisms in the same directorate (for example, the Mathematical Sciences Postdoctoral Research Fellowships, MSPRF, for mathematics) and confirm current solicitation status for each before building an application timeline around it.
For the general structure shared across NSF’s postdoctoral fellowship programs — individually held versus grant-funded staff positions, typical term length, stipend-plus-allowance award structure — see CASRAI’s NSF Postdoctoral Fellowship entry and, for the equivalent NIH mechanism, the F32 NIH Postdoctoral Individual NRSA Fellowship entry. For NSF’s proposal-preparation baseline that sits underneath every individual solicitation, see NSF PAPPG.
