Science Olympiads for High Schoolers: USABO, USNCO, USAPhO

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USABO, USNCO, F=ma and USAPhO, USESO, USAAAO and NACLO: who runs each science olympiad, how to enter, the rounds, costs and the 2026-27 dates posted so far.

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The U.S. science olympiads are the selection contests for the international olympiads in biology, chemistry, physics, earth science, astronomy and linguistics. Each starts with a first-round exam and narrows, over a few rounds, to a small team that represents the country abroad. Even if you never get near that team, the first rounds are a good test of how far past your class you can go.

Most of them share one rule that surprises students: you usually can't enter alone. A school registers, a teacher proctors, or you find an approved host. This guide covers who runs each olympiad, how you get in, the rounds, what it costs and the 2026-27 dates posted so far. We checked each organizer's own pages on September 26, 2026 and rechecked them on September 27, 2026. Several olympiads hadn't posted 2027 dates yet, so for those we give last season's schedule as a guide.

The Olympiads at a Glance

OlympiadRun byHow you enterNext dates posted
USABO (biology)Center for Excellence in EducationThrough a registered host schoolOpen Exam: February 3, 2027
USNCO (chemistry)American Chemical SocietyThrough your USNCO Coordinator2027 dates not yet posted
F=ma and USAPhO (physics)American Association of Physics Teachers (AAPT)A school (or homeschool parent) registers you; approved proctor2027 registration opens mid-October
USESO (earth science)United States Earth Science OrganizationRegister yourself, with a verified proctorRegistration usually opens around December
USAAAO (astronomy)USA Astronomy and Astrophysics OrganizationYour proctor registers you2027 dates not yet posted
NACLO (linguistics)North American Computational Linguistics Open CompetitionAt a registered university or high school siteRegistration opens October 5, 2026; Open Round January 28, 2027

USABO: Biology

The USA Biology Olympiad, which also goes by the USA Biolympiad, is administered by the Center for Excellence in Education (CEE). It is school-based: there are no individual registrations. A teacher registers the school as a test administrator and pays $125 per school, and students register only after their teacher confirms the school is signed up.

  • Who: students in grades 9-12. Seniors are eligible if they haven't formally enrolled in a college program. Homeschoolers can take the exam at a local high school, arranged before registration closes, and may be responsible for the $125 fee. If your school isn't participating, you can ask USABO to find a host school, but it can't guarantee one.
  • Round 1, the Open Exam: a 50-minute online multiple-choice test, proctored in person at a registered school. Citizenship isn't required for this round.
  • Round 2, the Semifinal: a 120-minute online exam for students who score in the top 10% of the Open Exam and are U.S. citizens or green card holders.
  • National Finals: 20 finalists attend a 12-day residential program at a host university, with room and board provided. Students pay their own transportation, and CEE asks students with financial need to contact it. Four finalists become the U.S. team for the International Biology Olympiad.

2026-27 dates: schools must pay the $125 fee by October 23, 2026, and school registration closes November 15. Student registration closes November 22. A practice exam runs January 8-22, 2027, the Open Exam is February 3, 2027 at 4 p.m. Eastern, and the Semifinal is March 2, 2027. National Finalists are announced March 30, the Finals run June 20-30, 2027, and the 2027 International Biology Olympiad is in Warsaw, Poland, July 18-25. USABO is also asking schools willing to host homeschooled students or students from non-participating schools to say so by October 20, 2026.

USNCO: Chemistry

The American Chemical Society has sponsored the U.S. National Chemistry Olympiad since 1984. It has four tiers:

  • Local exams in March, run by ACS local sections. Registering doesn't guarantee a seat; your local section coordinator notifies you, and coordinators choose nominees for the national exam from the local results.
  • The National Exam in April, a three-part exam taken by more than 1,000 students, often hosted by local sections at colleges and universities.
  • Study Camp: the 20 top scorers on the national exam spend two weeks at a study camp in June.
  • The International Chemistry Olympiad: four students from the camp represent the U.S. in July.

ACS says parents and guardians who want to register students for the 2027 USNCO must contact their USNCO Coordinator, and its site has a coordinator finder. It hadn't posted 2027 dates when we checked. Last season's schedule: student registration opened October 6, 2025, local exams ran February 27 to March 16, 2026, the national exam April 10-19, and the study camp May 31 to June 13. Ask your chemistry teacher to contact the coordinator early in the school year.

F=ma and USAPhO: Physics

The American Association of Physics Teachers and the American Institute of Physics sponsor the competition that picks the U.S. team for the International Physics Olympiad. It has three stages:

  • F=ma: a 75-minute, 25-question multiple-choice exam on mechanics. AAPT says every problem can be solved without calculus.
  • USAPhO: about 400 students are invited based on their F=ma scores. It is a 3-hour free-response exam in two 90-minute parts, covering all of introductory physics, and it may require calculus.
  • The U.S. Physics Team: about 20 students are invited, based on USAPhO and F=ma scores, to a ten-day training camp at the University of Maryland. Five are chosen for the International Physics Olympiad.

Eligibility: F=ma is open to U.S. citizens, green card holders and students currently attending a U.S. school. USAPhO requires citizenship or a green card. For both, you must be located in the U.S. when you test. Camp invitees must not exceed age 20 by June 30 of the competition year.

How to enter: a teacher or school registers students, and AAPT prefers one person to register everyone from a school. Parents of homeschooled students may register them but must name a separate proctor. For 2026 the fee was $75 per school ($37.50 for AAPT members) plus $15.50 per student. Both exams must be proctored in person, and parents, relatives and close friends can't proctor; for-profit test-prep centers can't either. Homeschooled students are told to ask community colleges, universities or libraries. For 2026, both exams moved online through Educational Vistas.

Dates: AAPT says registration for 2027 will open in mid-October. Last season, the F=ma registration deadline was January 20, 2026 (extended to January 21), the F=ma exam was February 12, USAPhO was April 10, and the training camp ran May 30 to June 9, 2026.

If F=ma feels like a big first step, AAPT's PhysicsBowl is a 40-question, 45-minute multiple-choice test, taken at school, on topics from a typical high school physics course. Schools compete regionally, and registration for 2027 opens in December.

USESO: Earth Science

The United States Earth Science Organization runs the National Open Exam, the first step toward its training camp and the U.S. team for the International Earth Science Olympiad. Unlike most olympiads, you register yourself, but you need a verified proctor:

  • Proctors: a teacher or administrator at your school, or a professional testing center, who has completed USESO's verification form using an email address that matches their organization's website. A proctor can't be related to you.
  • Cost: for 2026, USESO moved to a "pay what you can afford" model: $25 standard registration, or $5 for students with financial need.
  • Training Camp: up to 40 students are invited, based on the exam, to a week-long residential camp in June. Camp eligibility: grades 9-12, at least 15 years old by the first day of camp, working proficiency in English, and U.S. citizenship or a green card. The 2026 camp cost $2,600, with need-based aid available. The top four students form the U.S. team, and you need a valid passport to qualify.

Dates: USESO says National Open Exam registration usually opens around December, and it hadn't posted 2027 dates when we checked. Last season, registration opened December 1, 2025, closed February 28, 2026, proctors had to be verified by March 7, and the exam window was March 19-23, 2026.

USAAAO: Astronomy and Astrophysics

The USA Astronomy and Astrophysics Organization selects the U.S. team for the International Olympiad on Astronomy and Astrophysics (IOAA). Its 2026 cycle had three proctored rounds:

  • First Round: about 75 minutes and about 30 multiple-choice questions, taken online and proctored in person by a teacher at your school. The proctor completes the registration form.
  • National Astronomy Competition (NAC): about 2.5 hours of free response, for students above the first-round cutoff (17 in 2026).
  • Third Round: the top 15 U.S. citizens or permanent residents from the NAC join free online training and take a theory and practical exam. The top five, ranked 40% on the NAC and 60% on the third round, represent the U.S. at the IOAA.

In 2026, registration was $30 per student, or $20 each if at least five students from a school registered, with a financial aid form for students who couldn't pay. Any student may take the exams, but only U.S. citizens and permanent residents can make the team. Last season, registration ran January 1-31, 2026, the first round was February 9 and the NAC was April 13. The 2026 IOAA runs September 25 to October 5 in Hanoi, Vietnam, and USAAAO hadn't posted 2027 dates when we checked.

NACLO: Linguistics

In the North American Computational Linguistics Open Competition, high school students solve linguistics puzzles built from real languages. NACLO says no prior knowledge of linguistics or second languages is necessary. Its top students go on to the International Linguistics Olympiad (IOL).

  • 2027 dates: student registration opens October 5, 2026. The Open Round is Thursday, January 28, 2027, and the Invitational Round is Thursday, March 18, 2027.
  • Where: in person at a registered site: a university site, or a high school site run by a teacher or librarian.
  • Cost and eligibility: NACLO's 2026 Student Handbook says participation is free for all eligible students. To take part, you must never have enrolled as a full-time college student, be younger than 20 on the first day of the IOL, and be a citizen of the U.S. or Canada or enrolled in a secondary school there.
  • Rounds: in 2026, the Open Round was three hours and the Invitational Round four. Top scorers in the Open Round advance to the Invitational, and its top four or eight U.S. students and top four Canadian students are chosen for the IOL.

How to Get Started This Year

  • This week: ask the teacher who would run each olympiad (biology, chemistry, physics) whether your school registers. USABO's school payment deadline is October 23.
  • In October: register for NACLO once it opens on October 5, and watch for F=ma registration in mid-October.
  • Over the winter: work through past exams. AAPT, USESO and USAAAO post them on their sites.
  • If you love computing too: the USA Computing Olympiad picks the informatics team; see our coding competitions guide.

A national olympiad is hard, and most students who take a first round won't advance. That's fine. Studying for one can take you well past your textbook, and that's worth describing on an application. See our guide to writing activity descriptions.

Where to Go Next

Browse olympiads, biology, chemistry and physics programs, or read about math competitions and the science fair path to ISEF. Save the olympiads you pick to the Activities Builder so their deadlines stay in front of you.

Sources

Facts in this article were last reviewed against these sources on . Programs change their dates and prices; confirm on the official page before you apply.

Frequently Asked Questions

Can I take a science olympiad if my school doesn't participate?

Often, yes, but you need an approved host or proctor. USABO lets students ask to register with another school through its "My school is not participating" feature, though it can't guarantee a host. For F=ma, homeschoolers are told to ask community colleges, universities or libraries about proctoring; parents and relatives can't proctor. USESO accepts a teacher or administrator from your school or a professional testing center. For NACLO, you can compete at a registered university site or find a teacher or librarian to run a high school site.

Do I need to be a U.S. citizen to compete?

Not always for the first round. USABO's Open Exam doesn't require citizenship, but the Semifinal does (U.S. citizens or green card holders). F=ma is open to citizens, green card holders and students attending a U.S. school, while USAPhO requires citizenship or a green card, and both require you to be located in the U.S. USAAAO lets any student take its exams, but only citizens and permanent residents can make the U.S. team.

Which science olympiad is best for a beginner?

Start with the one that matches a class you've taken or are taking. NACLO needs no prior knowledge of linguistics or other languages. AAPT's PhysicsBowl is a 40-question test based on topics in a typical high school physics course. F=ma covers mechanics, and every problem can be solved without calculus. AAPT, USESO and USAAAO post past exams on their sites, so try one before you register.

Can I compete in more than one olympiad?

You can take several first-round exams, since they fall on different dates. The catch comes at the top: USABO National Finalists and their guardians sign an agreement that prohibits participating in any other national academic olympiad or summer program, such as the Research Science Institute. Check each olympiad's rules before you commit to a summer camp.

How much do the science olympiads cost?

It varies. USABO charges schools $125 each. For 2026, F=ma cost $75 per school ($37.50 for AAPT members) plus $15.50 per student. USESO's Open Exam was $25, or $5 for students with financial need. USAAAO's first round was $30 per student, $20 if at least five students from a school registered, with financial aid available. NACLO is free for eligible students.

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