By Dr. Harman Brah, MD · Judge, California Science & Engineering Fair
Regeneron STS is a written application for seniors, judged mostly on a research paper. Regeneron ISEF is a science fair for grades 9 to 12 that you reach by winning a local fair, judged mostly at the board. Many strong students do both, often with the same project.
The short comparison
| Regeneron STS | Regeneron ISEF | |
|---|---|---|
| Who | Last year of secondary school, in the US and its territories | Grades 9 to 12, selected by an affiliated fair |
| How you enter | Apply directly | Win at a Society-affiliated fair |
| Main format | A maximum 20-page original scientific paper, plus recommendations | A project board and interviews with judges |
| Team projects | Not eligible | Allowed at ISEF-affiliated fairs |
| 2026-27 timing | Applications close November 5, 2026 | County fairs in March, state fair in April, ISEF in May 2027 |
Choose STS if
- your student is a senior this year
- the research is individual and substantially their own
- they write well and can explain the work on paper
STS is a one-shot competition, and around 2,600 students enter each year. The top 300 Scholars each receive $2,000, with $2,000 more going to their school, and the top 40 Finalists compete for awards including a $250,000 first prize.
Choose ISEF if
- your student is in grades 9 to 11, or a senior who missed STS
- they are strongest talking through the work in person
- the project was done with a partner
The path runs through the county fair: the Synopsys Championship in Santa Clara County, the Alameda County fair, the San Mateo County STEM Fair or the Contra Costa County fair, then the state fair.
Why many students do both
The same project can usually serve both. A senior applies to STS by November 5 with the paper, then takes the project to the county fair in March. The paper sharpens the board, and the board practice sharpens the thinking.
The rules that matter for both: the work must be the student’s own, and for STS, entrants and mentors must disclose participation in paid programs.
Where we fit
We mentor students for both, and our students have been Regeneron STS and ISEF semifinalists and category award winners. Dr. Harman Brah judges at the California Science & Engineering Fair, which gives us the board-side view ISEF rewards. See our STS & ISEF track, or read what to finish before the STS deadline.
FAQ
Can I do both Regeneron STS and ISEF with the same project?
Usually yes. Many students apply to STS in the fall and take the same project to their county fair in the spring.
Can a team project enter Regeneron STS?
No. Only independent, individual research is eligible for STS.
Who can enter Regeneron STS?
Students in their last year of secondary school in the US and its territories, regardless of citizenship.
How do you get into ISEF?
By winning at a Society-affiliated local, regional, state or national fair. There is no direct application.
More guides on this topic
- Does Your Student Need a Research Mentor for STS or ISEF?
- Regeneron STS 2027: What to Finish Before the November 5 Deadline
- How to Qualify for ISEF From the Bay Area
- My Child Does Research in a University Lab, Do They Need Outside Help for Regeneron STS?
- Can Research Done in a Professor's Lab Be Submitted to Regeneron STS?
Planning a Science Fair or STS Project?
This guide is the general version. Work one on one with a physician who judges at the California state fair and a PhD chemist, on a project your student owns from the first question to the final poster.