North American Computational Linguistics Open Competition (NACLO): A Complete Guide

The North American Computational Linguistics Open Competition (NACLO) is a contest for middle and high school students in North America that challenges them with complex linguistic puzzles from various languages, testing logic and problem-solving skills to introduce them to computational linguistics and potentially qualify them for the International Linguistics Olympiad

In this blog, you’ll learn everything you need to know about NACLO: how the competition works, how to register, tips for preparing, past winners, and what it takes to qualify for the International Linguistics Olympiad (IOL).

• What is NACLO?
• NACLO Awards and Prizes
• How to Qualify for NACLO
• How to Get into NACLO
• How to Succeed in NACLO
• NACLO Previous Winners
• Frequently Asked Questions
• Takeaways

What is NACLO?

The North American Computational Linguistics Open Competition is a fun, logic-based contest where high school (and sometimes middle school) students solve real language puzzles. NACLO challenges you to uncover how different languages work using logical and analytical reasoning and pattern recognition. Examples of problems might include translating unknown languages, solving number or calendar system puzzles, or working with writing systems or speech transcriptions.

NACLO continues a long global tradition of linguistics competitions that began in Moscow in the 1960s and later spread to countries like Bulgaria, the Netherlands, and the United States. These contests challenge students to solve language puzzles using logic and reasoning rather than memorization.

Building on that legacy, NACLO adds a modern twist by combining linguistics with computational thinking, which allows students to explore how languages work while developing problem-solving skills that are useful in computer science and beyond.

Here’s an overview of what it is and how it works:

• Contests per year. NACLO has two main rounds: the Open Round in January and the Invitational Round in March. Winners from the Invitational Round can earn a spot on the U.S team for the International Linguistics Olympiad.
• Format. Students work individually or in teams to analyze and solve linguistic problems using clues and data from unfamiliar languages.
• Problems. Each puzzle is like a code. Your goal is to figure out what the data means and how the language operates.
• No experience required. You don’t need to know any foreign languages or prior linguistics concepts—just logic and curiosity.
• Recognition. Top performers from the Invitational Round can qualify to represent the U.S. or Canada at the International Linguistics Olympiad (IOL), where they compete with teams from around the world.

NACLO is your chance to explore how human language connects with computational thinking. It’s challenging, creative, and a great way to sharpen your problem-solving skills.

NACLO Important Dates

Each year, NACLO follows a clear timeline that includes registration, two main competition rounds, and international representation for top participants.

Below is the 2024–2025 schedule with key events and updates based on official announcements:

NACLO Awards and Prizes

NACLO honors top-performing students and teams for their excellence in solving complex language puzzles through logic and reasoning. Awards celebrate both individual achievement and teamwork, with distinctions for creative problem-solving, high scores, and representation at the International Linguistics Olympiad (IOL).

Here are the awards and recognition given out every year:

Individual Awards

• Medals (Gold, Silver, Bronze). Presented to students who earn top scores in the Invitational Round.
• Honorable Mention. Given to participants who perform above average or show exceptional analytical skill.
• Best Solution Award. Recognizes the most elegant or insightful solution to a specific problem.

Team Awards

• Team Medals. Granted to U.S. and Canadian teams for strong collective performance at the IOL, such as USA Red earning top placements in recent years.
• Top Team Trophy. Awarded to the team with the highest combined individual scores during international competition.

Other Recognition

• International Representation. Students selected for the U.S. and Anglophone Canada teams automatically receive national recognition for qualifying to compete at the IOL.
• IOL Hall of Fame. Honors participants who have earned multiple medals across different years, showcasing consistent excellence in linguistic problem-solving.

How to Qualify for NACLO Finals

To reach the top rounds in NACLO, you must start with the Open Round, then perform well enough to move to the Invitational Round. From there, the best may be chosen for the international team and compete on the world stage.

Before you aim for the finals, here’s who can participate and under what conditions:

Eligibility

First, everyone who applies (middle school or high school level) can take part in the Open Round, which serves both as an introduction and a filter. Strong scorers in that round are invited to the Invitational Round, which is harder and is used to pick candidates for the U.S. and Canadian teams to compete at the International Linguistics Olympiad (IOL).

To be eligible, you must:

• Be enrolled in a U.S. or Canadian secondary school (or be a citizen/student in those countries)
• Be under 20 years old on the first day of the IOL
• Have never been a full-time college or university student
• Compete at an approved site (high school, university, or authorized location)

Once you qualify through the Invitational Round and satisfy IOL rules, you may be selected to represent your country (U.S. or Canada) at the International Linguistics Olympiad.

Process

Take note of the following before signing up for NACLO:

• For the Open Round, you simply register online through the NACLO website or your local contest site.
• For the Invitational Round. Students who qualify automatically advance and may be asked to confirm eligibility (such as age or enrollment status).
• For International Competition (IOL). Selected students will need to submit additional paperwork, including consent forms for minors and travel documentation for team participation abroad.

Contest fees

NACLO is completely free to join at every stage. Students invited to represent the U.S. or Canada at the International Linguistics Olympiad typically have their travel and lodging expenses sponsored by NACLO or partner institutions. Families may only need to handle small personal or incidental costs.

Registration deadline

Make sure you keep track of these important NACLO registration dates and details:

• Online registration. Opens on October 10, 2024, and closes on January 16, 2025, at 10 PM EST. You can register directly on the NACLO website.
• Open Round. Scheduled for January 23, 2025. Registration must be completed before this date to participate.
• Invitational Round qualification. Only those who qualify from the Open Round will advance to the Invitational Round on March 13, 2025.
• Invitational results and team selection. Final results and IOL team announcements will be released on April 26, 2025.

Timely registration ensures you don’t miss any stage of the competition.

How to Get Into NACLO

Getting into NACLO is a matter of following the registration steps, competing in the rounds, and advancing based on your scores.

Take a look at these detailed steps to help you get started:

1. Understand the eligibility and rules.

Timeline: Before registration opens

Read the official Student Handbook (or latest handbook) and the contest rules. The handbook contains important details—such as eligibility, general rules, and scoring. If you have questions that the handbook doesn’t cover, don’t hesitate to contact [email protected].

2. Register to participate.

Go to the NACLO registration page and sign up as a student when registration opens in the fall.  Then, choose a test site (your high school if it hosts NACLO, or a nearby university site). If you can’t find a nearby site, contact NACLO for help. Registration is free.

3. Compete in the Open Round.

The Open Round is an in-person exam (not online) typically held in January.  Arrive early (often 30–45 minutes before the start time).  The contest booklets will be distributed at the start time, rules read, and then you solve problems during the allotted duration.  You must write your answers with a black pen in the provided answer spaces. Scratch work is allowed on extra paper.

4. Advance (if your score is high enough).

Top scorers from the Open Round are invited to the Invitational Round after results are released. Check the official site or your student portal for the qualification cutoff and whether you made the cut.

5. Compete in the Invitational Round.

The Invitational Round typically occurs in March and is more challenging than the Open Round, since it’s designed to further distinguish top problem solvers.  Arrive by the set time, listen to instructions, and work through the problems in the allotted time.  You may take it at your assigned site (often the same or a regional site) unless a special arrangement is granted.

6. Possible selection to the International Linguistics Olympiad (IOL).

If you score among the top in the Invitational Round, you may be selected to represent the U.S. or Canada in the International Linguistics Olympiad, provided you fulfill IOL eligibility requirements. It’s important to note that if you are eligible for both U.S. and Canadian teams, you must declare which country’s team you aim for before the Open Round.

7. Track key dates (and plan your schedule).

Track the following important dates as soon as they’re published on the NACLO website:

• Registration opening and closing dates
• Open Round date and start times across time zones
• Invitational Round date and details
• IOL event dates (usually in summer)
• Deadline for declaring U.S. or Canada team, if needed

How to Succeed in NACLO

Excelling at NACLO takes curiosity, patience, and steady practice in solving logic and language puzzles. You don’t need prior knowledge of linguistics—just a willingness to think critically and recognize patterns. Here’s how you can prepare effectively and perform your best on competition day.

1. Understand what NACLO is all about.

Before anything else, learn what the competition entails. NACLO challenges students to solve linguistic puzzles that reveal how human languages work. Problems are self-contained—you’ll get all the information you need in the task itself. The secret is to think like a detective: use clues, patterns, and reasoning to uncover how the language system operates.

2. Learn the format and rules.

Read the official Student Handbook carefully. Understand eligibility requirements, contest structure, allowed materials (pens, pencils, scratch paper), and prohibited items (electronic devices, dictionaries, or collaboration). Knowing these rules ahead of time prevents small mistakes that could cost you points or result in disqualification.

3. Get familiar with the types of problems.

Spend time exploring the practice problems, sample problems, and previous years’ problems—all on NACLO’s website. These are real puzzles from past NACLO contests, complete with solutions and explanations. Start with sample problems to get comfortable with how clues are structured, then work your way up to older Invitational-level problems.

As you practice, focus on identifying common reasoning patterns like word order, case marking, sound correspondences, and number systems.

4. Develop logical reasoning skills.

NACLO isn’t about memorization. Instead, the secret lies in pattern recognition and systematic thinking. Practice breaking puzzles into smaller steps with these quick steps:

• Identify what information is given and what’s missing.
• Build tables or charts to organize data.
• Test hypotheses and eliminate inconsistencies.
• Work on puzzles from logic books, online riddles, or even Sudoku to sharpen your deductive skills.

5. Simulate contest conditions.

When practicing, mimic real NACLO timing, which is typically three hours for the Open Round. Use only a pen or pencil, avoid online help, and time yourself strictly. This builds stamina and helps you learn how to manage your time across multiple problems of varying difficulty.

6. Keep practicing and stay consistent.

Success at NACLO comes from steady practice and curiosity about language. Even outside the contest season, continue solving puzzles from past years, read about linguistic phenomena (like syntax, phonology, or morphology), and challenge yourself with new problem types. Over time, your ability to see patterns and reason through complex data will naturally improve.

NACLO Previous Winners

The North American Computational Linguistics Open (NACLO) recognizes top-performing students who demonstrate exceptional reasoning and linguistic problem-solving skills. The organizers do not publicly release the full names of Gold, Silver, Bronze, and Honorable Mention awardees, only their initials.

However, they do provide complete names of those who qualify for the International Linguistics Olympiad (IOL), including alternates. In addition, NACLO highlights the winners of the Best Problem Results & Best Solution Awards.

Here are the students who qualified to represent the United States at the 2025 International Linguistics Olympiad (IOL), held in Taiwan from July 22–27, 2025, along with the designated alternates.

Best Problem Results & Best Solution Awards

The Best Problem Results & Best Solution Awards recognize participants who achieved the highest scores or produced outstanding solutions for specific problems in the NACLO Invitational Round. Here are students who had the best solutions:

Frequently Asked Questions

1. Who can participate in NACLO?

Any middle or high school student in the United States or Canada can participate in the North American Computational Linguistics Open (NACLO). You don’t need prior knowledge of linguistics—just strong logical thinking and problem-solving skills.

2. What happens if I perform well in NACLO?

Top scorers from the Open Round advance to the Invitational Round, where the problems are more challenging. From there, the highest-performing students may qualify to represent the United States or Canada at the International Linguistics Olympiad (IOL).

3. How is NACLO structured?

NACLO consists of two rounds: the Open Round (held in January) and the Invitational Round (typically in March). Each round features a set of linguistic puzzles that students solve individually under timed conditions, usually lasting about three hours.

4. Is NACLO a prestigious competition?

Yes, NACLO is one of the most respected academic competitions for high school students in North America, being highly regarded among universities and academic circles for demonstrating analytical ability and intellectual creativity. It serves as the official pathway to the International Linguistics Olympiad (IOL).

5. How valuable is excelling in NACLO for college admissions?

Performing really well in NACLO, especially qualifying for the Invitational Round or the IOL, is considered a Tier 1 academic achievement. It reflects advanced problem-solving, logical reasoning, and linguistic analysis skills, which are highly valued by selective universities and scholarship programs.

Takeaways

• Competing in NACLO shows that you can analyze complex linguistic systems and solve logic-based puzzles under pressure, a skill that stands out in both academics and beyond.
• The NACLO 2025 season runs from January through March, with the Open Round taking place in January and the Invitational Round in March.
• Top participants from the Invitational Round may qualify to represent the United States or Canada at the International Linguistics Olympiad (IOL).
• Top Invitational competitors often demonstrate exceptional reasoning, creativity, and persistence when faced with unfamiliar languages and problem types.
• A college admissions expert can help you present your NACLO accomplishments in a way that highlights your analytical ability, logical thinking, and recognition at both the national and international levels.