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 19, 2021The handbook for 2022 is now available.
  • September 15, 2021Registration for the 2020 Open Contest will start in late September, 2021.
  • August 31, 2021Press Release about the performance of the NACLO teams at the 2021 IOL.
  • August 16, 2021NACLO 2022 will be on January 27 and March 17, 2022
  • July 19, 2021Press Release for the NACLO 2021 contest.
  • April 16, 2021Grading for the 2021 Invitational Round has concluded. The results can be accessed here. The Open Round and Invitational Round problems and solutions will be posted shortly. Thank you for participating!
  • February 27, 2021Grading for the 2021 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.
  • February 26, 2021The scores from the Open Round will be posted tomorrow, Saturday, February 27.
  • February 1, 2021The NACLO 2021 Open Round took place on January 28, 2021. Results and invitations to the Invitational Round will be announced on or around February 28. If you missed this year's contest, registration for next year's contest will open in September 2022.
  • January 15, 2021The new registration deadline is Friday, January 22.
  • January 8, 2021 All participants enrolled to participate in the NACLO Open Round on January 28, 2021, from home (At-Home Site) should have received an email directly from NACLO with the subject line “NACLO 2021 At-Home Participants / Important Instructions.” Any At-Home participant who has not received this email should immediately contact naclo21org@umich.edu. All At-Home participants should check the email they used to register for the competition regularly for further instructions.
  • December 17, 2020 This year's student registration deadline for the At-Home option is January 15, 2021, and must be strictly enforced to give NACLO the required time to ensure all At-Home participants are individually set up for the January 28 Open Round.
  • December 17, 2020The NACLO YouTube Channel is live now. We will be uploading new videos hosted by past team participants during which they walk us through their process for solving a NACLO or IOL problem.
  • October 1, 2020The NACLO 2020 Press Release.
  • September 20, 2020The handbook for 2021 is now available.
  • September 20, 2020Registration for the 2021 Open Contest started on September 15, 2020.
  • September 2, 2020Students who cannot participate at a high school or university site due to COVID-19 restrictions have the one-time option of participating in the open round of NACLO 2021 from home by registering for the AT-HOME site, one of the options available in the University Sites category. Participants registering for this site must have internet access for the duration of the competition in order to receive the puzzles directly from the NACLO organizing committee and print them at home, communicate with the jury if needed, and enter their puzzle answers online using Google Forms.
  • August 23, 2020The NACLO organizing committee is mindful of the health and safety of its participants and its site hosts. In light of the COVID-19 pandemic, participants and hosts are encouraged to follow the direction of state, provincial, and local officials to determine the safest option for hosting the NACLO 2021 Open Round on January 28, 2021, as well as the Invitational Round on March 11, 2021. As health-related restrictions remain fluid across different parts of the U.S. and Canada, we encourage students to register as in the past keeping in mind that the contingency plan is for students to participate from home if they find themselves unable to participate at a University or High School site due to restrictions related to COVID-19. Please note that this at-home participation option will require internet access for the duration of the competition.
  • June 14, 2020All Open Round problems (+solutions) have been posted online under STUDENTS/PRACTICE PROBLEMS tab.
  • March 30, 2020See the results of the Invitational Round. If your score is missing or if you notice any other problem, please contact naclo21org@umich.edu asap. Please note that announcement of team qualifiers and alternates will be intentionally delayed. Further information about teams will be released in the next several days, pending further guidance from the IOL.
  • March 10, 2020The list of submitted booklets for the Invitational Round is now available. If you don't see your number here, please contact naclo21org@umich.edu asap
  • February 15, 2020Grading is over (with a few exceptions). See the results. If your score is missing or if you notice any other problem, please contact naclo21org@umich.edu asap.
  • February 10, 2020The list of submitted booklets for the Open Round is now available. If you don't see your number here, please contact naclo21org@umich.edu asap
  • January 23, 2020On-site registration is open now for the sites that allow walk-ins. The registration site will be closed for good after the end of the contest later today
  • January 22, 2020Regular registration ends today (January 22) at 3 PM EST (12 noon PST). It will reopen for walk-in registration tomorrow (January 23) morning and close again for good after the end of the contest. If you are a student, you can check if your site allows walk-ins. All participants have to register in order to compete.
  • December 1, 2019Announcement about the new name of this competition.
  • September 7, 2019Registration for 2020 has started.

    Student registrations are not carried over from one year to the next. If you are a student and had registered prior to September 15, you will need to register again from scratch.

    Site registrations (high school and university sites) are automatically copied from one year to the next.

  • August 12, 2019 The dates for the 2020 contest are January 23 (open round) and March 5, 2020 (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 naclo21org@umich.edu.