International Logic Olympiad
Logic is everywhere—whether solving puzzles, playing games, or tackling school assignments across Math, History, and English. It's also the foundation of professional fields like computer science, engineering, medicine, and law, where reasoning and problem-solving are key.
Our contest challenges students to think critically and apply logical reasoning through sets and set operations—union, intersection, complement—and symbolic mathematics at a high school algebra level. Consider the following problem:
Suarez is a (slowly) recovering liar. He lies on six days of the week, but on the seventh day he always tells the truth. One week, he made the following statements on three successive days.

On which day does Suarez tell the truth?
If you have a sharp mind and a passion for logical thinking, put your skills to the test and prove your reasoning in this competition!
What is the ILO?
The International Logic Olympiad is the leading logic competition hosted annually in partnership with Stanford University to promote and internationalize logic education.
Offering high school students worldwide a chance to showcase excellence in logic and problem-solving, The ILO culminates in an on-campus final round at Stanford University during the summer.
Since 2024, we're proud to support:
6100+
Participants
104
Countries
3800+
Schools
Meet This Year's Winners
Congratulations to the winners of ILO 2026! Their logic, creativity, and determination led them to the top on the global stage.
ILO 2026 Junior

Left to right: Ryan Park, Muhammad Hamza Shafoat, Reed Li
ILO 2026 Senior

Left to right: Leo Zeng, Nathan Chen, Maximillian Yang
Partner With Us
ILO's reach is possible because of the organizations and individuals who support our mission. Whether you're looking to sponsor the competition or partner with us regionally, here's how to get involved.
Become a Sponsor
ILO is building a global competition that rewards clear, rigorous reasoning, made possible by the organizations that choose to invest in it. Support the next generation of logical thinkers.
Become a Regional Partner
Help bring ILO to students in your region. Learn what it means to be a regional partner and see the partners currently working with us around the world.
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