American Computer Science League (ACSL): A Complete Guide

Now in its 48th year, the American Computer Science League (ACSL) saw over 7,000 students from 21 countries participate in its most recent regular season competitions. With students competing across multiple levels each year, ACSL is regarded as one of the top computer science competitions for high school students worldwide.

In this guide, you’ll learn how ACSL works, who can participate, and how students qualify and advance through the competition. We’ll also cover ACSL’s awards, past winners, and helpful tips for performing well at each stage.

• What Is the American Computer Science League (ACSL)?
• American Computer Science League (ACSL) Awards and Prizes
• How to Qualify for the American Computer Science League (ACSL)
• How to Join the American Computer Science League (ACSL)
• How to Win the American Computer Science League (ACSL)
• American Computer Science League (ACSL) Previous Winners
• Frequently Asked Questions
• Takeaways

What Is the American Computer Science League (ACSL)?

The American Computer Science League (ACSL) is a non-profit organization that runs computer science and programming competitions for K–12 students in the U.S. and internationally. Founded in 1978, ACSL works with schools, organizations, and local groups to support computer science education through competitive problem solving.

Students compete in ACSL based on age group and skill level. During the regular season, students compete in teams, and schools may send more than one team per division. At the end of the season, students who advance compete individually in the Finals.

The regular season consists of four contests, all of which are completed online through the HackerRank platform. Each contest focuses on core computer science concepts, including algorithms, programming, data structures, and computer organization.

For the 2025–2026 season, each contest is available during the following windows:

• Contest #1: Available Oct. 20, 2025; closes Sunday January 11, 2026 @ 11:59pm EST
• Contest #2: Available Jan. 5, 2026; closes Sunday March 1, 2026 @ 11:59pm EST
• Contest #3: Available Feb. 2, 2026; closes Sunday April 12, 2026 @ 11:59pm EDT
• Contest #4: Available March 2, 2026; closes Sunday May 17, 2026 @ 11:59pm EDT

Based on scores from the regular season, top students in all divisions are invited to an online Finals competition. For 2026, Finals invitations are sent between May 1 and May 21, with the Invitational Finals held on Saturday, May 23, 2026, during Memorial Day weekend in the U.S.

American Computer Science League (ACSL) Awards and Prizes

ACSL recognizes students at different points during the competition season. Awards are primarily given in the form of certificates during the regular season and certificates plus prizes at the Finals level.

When a team registers, ACSL sends a certificate to the team advisor, who chooses the most deserving team member to receive it. This recognition is based on the advisor’s judgment and may reflect effort, improvement, or contribution to the team.

After the regular season ends, ACSL awards certificates to the highest-scoring students and teams in each division within each U.S. state, or by country for students outside the U.S.

Students who advance to ACSL Finals can earn additional recognition. In the Finals, top-scoring students in each division receive both a certificate and a prize, with prizes sent directly to students and certificates distributed through their team advisors.

How to Qualify for the American Computer Science League (ACSL)

To qualify for the ACSL competition, students compete in the regular season through their school. Before aiming for the Finals, here’s who can participate and how the qualification process works.

Eligibility

You can participate in the ACSL competition based on your grade level and programming experience. The ACSL divisions are as follows:

• Elementary division. Open to students in grades 3–6, this division serves as an introduction to competitive programming.
• Classroom division. Open to students in all grades, especially those taking AP Computer Science Principles and other computer science classes without a major programming component.
• Junior division. Best for junior high and middle school students up to grade 9 who are learning programming or have some coding experience.
• Intermediate division. Best for advanced junior high school students or high school students with little to no programming experience.
• Senior division. Best for high school students with programming experience, especially those taking AP Computer Science.

Within a division, a school may form one or more teams. Schools can choose to compete using either a 5-score or 3-score format, meaning the team score for each contest is calculated using the individual scores of the top five or three students. A 5-score team may include up to 10 students, while a 3-score team may include up to 6 students.

Required documents

To participate, your team must be registered by a team advisor, not by individual students. Your advisor completes the ACSL registration form with basic details such as your school name, contact information, and how many teams will compete in each division.

During registration, your advisor can also purchase downloadable collections of past ACSL contests, which are often used to help teams practice and prepare for the competition.

Contest fees

ACSL charges a registration fee for each team entered in a division, which varies based on the division and whether the team is the first or an additional team from the same school or organization.

• First team in a division: $175
• First team in the Elementary Division: $125
• Each additional team in a division: $150
• Each additional team in the Elementary Division: $100

Participating in ACSL Finals also includes a $35 fee per student. The invitation email includes a payment link. Once payment is completed, you’ll receive a HackerRank invitation and a form to sign up for a breakout room, if you choose to participate.

Registration deadline

The deadline to register for the 2025–2026 ACSL season is December 31, 2025. Team advisors must submit the registration form, contest fees, and all required details by this date.

The same December 31 deadline applies to any additional teams, which can be registered by submitting another registration form and checking the box indicating that a team has already been registered.

How to Join the American Computer Science League (ACSL)

To join the ACSL competition, you don’t apply on your own. Instead, you participate through your school, usually with the help of a teacher or advisor. Here’s how you can get started:

1. Learn how ACSL works.

Before you join a team, it helps to understand how the contest is structured and which division you’re eligible for. ACSL has five divisions—Elementary, Classroom, Junior, Intermediate, and Senior—each designed for different grade levels and experience levels. Knowing where you fit will help you understand what the contests look like and what skills are expected.

Here’s how each ACSL division works:

• The Elementary Division uses a 30-minute online test with six non-programming questions. Each contest focuses on one topic, with a different topic tested in each round.
• The Classroom Division is non-programming only and is often used by entire classes. Each contest includes a 50-minute online test with ten short-answer questions drawn from the Junior, Intermediate, and Senior divisions.
• The Junior Division introduces more challenging material. Each contest consists of a 30-minute, six-question short-answer test and a programming problem that must be completed within 72 hours.
• The Intermediate Division follows the same format as the Junior division. Each contest includes a 30-minute short-answer test and a programming problem completed within a 72-hour window.
• The Senior Division features the most advanced problems. Like the Junior and Intermediate divisions, each contest includes a 30-minute, six-question short-answer test along with a programming problem to solve within 72 hours.

Across all divisions, contests test fundamental computer science concepts, including number systems, Boolean algebra, and digital electronics. While the core topics are similar, the level of detail and difficulty increases at higher divisions. In divisions with programming components, problems are solved using Python, C++, or Java.

2. Join or start a team.

To participate in ACSL, you need to be part of an official team connected to your school. A good first step is to check whether your school already has a team you can join. This could mean asking a computer science teacher or checking with your school’s coding clubs. Many schools already participate in ACSL and are often open to adding new students.

Another option is to form your own team, which gives you more control over who you work with and how you prepare. Reach out to classmates or friends who are interested in coding, and consider sharing the opportunity through computer science classes, STEM clubs, or with help from a teacher.

3. Find a team advisor.

Once you have a group of interested students, the next step is finding a team advisor, who’s usually a teacher, such as a computer science, math, or STEM instructor. In some cases, an experienced older student or a professional from your community may also serve as an advisor, depending on your school’s policies.

Your advisor manages team registration, shares official materials, and helps keep your team on track throughout the season. Because advisors work closely with you over time, you may even ask them to write a recommendation letter for your college applications based on your effort and participation.

4. Register through your advisor.

Once your team and advisor are set, your advisor completes the online registration form so your team can compete in the regular-season contests. The form is also used to purchase optional study materials, such as past ACSL contests, which many teams use to prepare for the competition.

Schools may register multiple teams in the same division, making it possible for more students to participate.

5. Compete and work toward the finals.

After your team is registered, you can begin competing in ACSL contests during the official contest windows. For each contest, you’ll receive an email from HackerRank with a link to the short-answer portion of the test. If you’re in the Junior, Intermediate, or Senior Division, you’ll receive a second email with a link to the programming problem, which you complete separately.

Although ACSL is organized around teams, all contest work is completed individually. Students aren’t allowed to collaborate while taking tests or solving programming problems. Team scores are calculated using the top three or top five individual scores from each team, depending on the team format your school selected.

The Finals competition is also individual-based. To qualify, you must meet a minimum score of 28 points for the Junior, Intermediate, and Senior divisions, 24 points for the Classroom division, and 14 points for the Elementary division. Students who meet these thresholds are invited to compete in the Finals competition in May.

How to Win the American Computer Science League (ACSL)

Winning ACSL comes down to preparation, focus, and consistency. Here are some tips to help you perform your best throughout the season:

1. Understand the contest format.

Make sure you understand how ACSL contests work, including guidelines and any rules. Knowing what to expect helps you manage your time and avoid surprises during the season.

For starters, there are four regular-season contests, and once you join, you’re expected to participate in all four. Each contest is available online for two months, but there’s a firm deadline by which scores must be submitted, so avoid waiting until the last minute to complete a contest.

There are also strict rules about what you can and can’t use during a contest. Only paper and pencil or pen are allowed, and calculators aren’t permitted. You can’t connect to the internet to look up code snippets, solutions, or references, and getting help from teachers, teammates, or anyone else during the contest is also not allowed.

2. Practice regularly.

Consistent practice is the most effective way to improve your performance in the competition. ACSL provides official study materials, including a limited number of past contest problems, which you can use to get familiar with the test format and timing. These materials are organized by division, making it easier to focus on content that matches your level.

As you practice, take note of topics that feel more challenging and spend extra time reviewing them. Solving complex problems multiple times and reviewing solutions can help you build up speed and confidence.

3. Keep track of time.

Time management is super important in ACSL. Most divisions give you 30 minutes to answer five short-answer questions, while the Classroom division allows 50 minutes, so every second counts. Plan your time carefully, move on if a question is taking too long, and come back to it later. If you finish early, use the remaining time to double-check your answers for small mistakes.

If your division includes a programming problem, you’ll also have 72 hours of running time to complete it. The clock continues even if you log out and return later, so it’s important to plan when you’ll work on the problem instead of leaving everything until the last minute.

4. Take care of yourself.

ACSL contests can be intense, especially with strict time limits, so basic preparation outside of studying is still essential. Get enough sleep the night before, eat a proper meal beforehand, and avoid starting a contest when you’re rushed or distracted. Being well-rested and alert helps you think more clearly and catch careless mistakes.

No matter the outcome, each contest helps you build problem-solving skills and get used to solving difficult questions under pressure. Treat every round as practice for the next one, and use what you learn to improve as the season goes on.

American Computer Science League (ACSL) Previous Winners

In 2025, all regular-season contests and the Finals were held online through the HackerRank platform. That year, nearly 3,000 students from around the world competed across divisions, highlighting the scale and competitiveness of the American Computer Science League (ACSL).

For earlier results, ACSL publishes student leaderboards, team rankings, and Finals results on its official website. Results are archived by year and division and can be filtered by level (Senior, Intermediate, Junior, Elementary, or Classroom), making it easy to explore past seasons and top performers. Because the leaderboards are interactive and updated each year, they’re the most reliable way to view complete and current ACSL results.

Frequently Asked Questions

1. Is ACSL multiple choice?

Yes. The short-answer test is multiple choice. Most divisions have six questions, while the Classroom division has twelve. If your division includes a programming problem, that part is completed separately in HackerRank and is not multiple choice.

2. Is ACSL good for college applications?

Yes. ACSL is a well-established competition, and participating shows colleges that you can handle challenging computer science problems. Strong performance in the Junior, Intermediate, or Senior divisions, or qualifying for the Finals, can be especially helpful for students applying to top computer science schools.

3. How is ACSL different from other computer science contests?

ACSL is different because it combines school-organized teams with individual problem solving. It offers divisions from Elementary through Senior and tests both short-answer computer science concepts and programming, rather than focusing only on advanced coding. ACSL also runs multiple contests across the season, with team results based on the top individual scores, not a single one-day event.

Takeaways

• The American Computer Science League (ACSL) is an online computer science competition for K–12 students in the U.S. and internationally.
• Students compete through their schools in divisions ranging from Elementary to Senior, making ACSL accessible at many grade and experience levels.
• ACSL has four contests each season. Teams earn scores based on their highest-scoring members, but students compete individually in the Finals.
• Doing well in ACSL can strengthen your application to computer science and engineering programs at top STEM colleges.
• Need help preparing for ACSL or building a strong STEM profile for college? Work with an admissions expert to plan your activities and present them clearly in your application.