NACLO
North American Computational Linguistics Open Competition
Solve puzzles in languages you have never seen, with no prior linguistics knowledge required.
Run by NACLO, with Carnegie Mellon University and Brandeis University
Key facts
- Eligible grades
-
Grades 6 to 12, primarily aimed at grades 9 to 12. The Open Round is open to all interested middle school and high school students.
Stated by NACLO host sites at the University of Maryland and Stanford. naclo.org's own front page describes the contest as for high school students, so middle schoolers should confirm their chosen site accepts them.Source, checked 2026-09-02
- Eligible ages
-
Not confirmed. This organiser may set eligibility by grade rather than age. We do not convert one into the other.NACLO sets eligibility by school level, not age.
- Individual or team
- Individual
- Where it runs
- In person · United States, Canada
- Entry cost
- FreeParticipation is free thanks to sponsor support, confirmed by several host sites.
- Registration deadline
- Set locally, not published as a single national date 2027 registration deadline not published. Host sites set their own advance cut-offs a few days before the Open Round.
- Competition dates
- 2027 dates not yet published. For reference, the 2026 Open Round was Thursday 29 January 2026 and the Invitational Round Thursday 19 March 2026, with the International Linguistics Olympiad in Bucharest in July 2026.
- Difficulty
- Some preparation neededYou will want a few weeks of targeted practice. Most motivated students place respectably.
- Prizes
- Recognition and selection for the North American teamsMedals and awards are given after the Invitational Round; no cash prizes are described on the pages checked.
What NACLO is
NACLO gives you problems written in languages you almost certainly do not speak, from Georgian to Nahuatl to invented writing systems, and asks you to work out the rules by pure deduction. No linguistics background is needed or expected, which makes it one of the most level playing fields in competitive academics. Top scorers advance to an invitational round and then to the team representing North America at the International Linguistics Olympiad.
How the competition works
Two rounds. The Open Round, held at a university host site or at your own school, identifies strong contestants who advance to the Invitational Round. Problems require no prior knowledge of linguistics or any language and are solved by analytic reasoning. The Invitational Round problems are harder.
Eligibility notes
Open to any secondary student in the United States or Canada. No linguistics or foreign language knowledge is assumed or advantageous.
Is NACLO right for you?
- Experience needed
- None. This is genuinely a first competition, and students with no linguistics exposure regularly outscore those who have studied it.
- Time commitment
- Ten to twenty hours of past-problem practice is enough to be competitive in the Open Round.
- What you actually do
- You sit alone with a paper of six to eight puzzles. A typical problem gives you twenty sentences in an unfamiliar language with English translations, then asks you to translate new sentences both ways. Everything you need is on the page.
A good fit if
- You like logic puzzles and cryptic crosswords
- You want a competition where preparation time is measured in hours, not seasons
- You are curious about languages but do not speak many
Probably not for you if
- Students who want a team experience
- Students looking for cash prizes
Common mistakes
- Assuming you need to know the language. You do not, and recognising a word can even mislead you.
- Not writing out the rule explicitly before translating. The problems reward stating the pattern, and several award points for the explanation.
- Spending the whole session on the first problem. The papers are deliberately not ordered by difficulty.
How to register
- Find a host site near you on the NACLO site, or ask a teacher to register your school as a proctored site.
- Register online during the autumn window. Registration is free.
- Work through past problems, which NACLO publishes in full with solutions.
- Sit the three-hour Open Round on the scheduled date.
What skills you need
- Pattern recognition
- Deductive reasoning
- Working systematically under time pressure
- Tolerance for unfamiliar notation
Recommended resources
-
NACLO official site with the full problem archive
Registration, host site list, and every past problem with full solutions.
-
NACLO practice problems
Organised by year, with official solutions. The single preparation resource you need.
-
International Linguistics Olympiad past problems
Harder international papers, free, useful for the Invitational Round.
Past problems and materials
Only materials the organiser or an authorised archive publishes openly are listed here.
- Complete NACLO archive with solutions
Published free by the organisers.
Frequently asked questions
Do I need to know another language?
No. NACLO problems are self-contained and everything needed to solve them is on the page. Knowing the specific language would be a disadvantage, since the problems are chosen precisely because almost nobody knows them.
How do I take it if there is no host site near me?
NACLO allows students to sit the Open Round at their own school with a teacher acting as proctor. Contact the organisers through the site during registration.
Reviews, tips and resources from other students
Posts are public. Do not share your full name, school, address or contact details.
Something out of date?
If a deadline, fee or eligibility rule on this page no longer matches the official site, flag it and it goes into the review queue.
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