What is NACLO?

NACLO is a contest in which high-school students solve linguistic problems. In solving these problems, students learn about the diversity and consistency of language, while exercising logic skills. No prior knowledge of linguistics or second languages is necessary. Professionals in linguistics, computational linguistics and language technologies use dozens of languages to create engaging problems that represent cutting edge issues in their fields. The competition has attracted top students to study and work in those same fields. It is truly an opportunity for young people to experience a taste of natural-language processing in the 21st century.


  • September 26, 2023Registration is now open for the Open Round of the competition on January 25, 2024! Register Here! The Invitational Round of the competition will be March 14, 2024.
  • April 10, 2023Grading for the 2023 Invitational Round has concluded. Participant scores, best problem solution awards, and the USA and Anglophone Canada team assignments for the 2023 IOL can be accessed here. The Open Round and Invitational Round problems and solutions will be posted shortly. Thank you for participating!
  • February 25, 2023Grading for the 2023 Open Round has concluded and your score is available in your student account. The list of students who have qualified for the Invitational Round has been released. You can access it here. Please contact nacloinquiries@googlegroups.com if your score is missing.
  • February 16, 2023The following booklets have been uploaded to the system for grading. If you don't find your submission here, please contact your site host immediately.
  • January 26, 2023The 2023 NACLO Open Round took place on January 26, 2023. Registration is now closed for this academic year. We thank all hosts for hosting and all participants for joining this year's contest. The jury will be grading over the next month and plans to post the Open Round scores by March 1, and participants will see their scores by logging into their individual accounts.
  • September 21, 2022The handbook for 2023 is now available.
  • September 20, 2022Registration for the 2023 Open Contest is now open.
  • September 18, 2022NACLO 2023 will be on January 26, 2023 (Open Round) and March 16, 2023 (Invitational Round).

Please Donate

You can help support NACLO either by mailing a check or giving online. For more information on both, please see our donations page. We thank you for your support!


We're looking for new sites and problem contributors. Please contact us at nacloinquiries@googlegroups.com.