About

NACLO runs in two rounds, both administered in person at registered sites. The Open Round, held each January, is open to all interested students and consists of 6–12 linguistic puzzle problems to be solved in three hours; problems draw on real languages from around the world — including endangered and constructed languages — and require no background knowledge, only the ability to identify patterns, reason about structure, and apply consistent logical rules. Approximately the top 10% of Open Round participants advance to the Invitational Round in March, a more difficult four-hour examination. From Invitational Round results, the top 4–8 US students are selected to represent the United States at the IOL, held each summer in a rotating host country; a second US team of 4 additional students may also be invited. Participation at all levels is free.

NACLO's "no prerequisites" claim is genuine and matters editorially. The puzzles require no linguistic knowledge — a student who has never studied a second language and has never heard the word morphology can perform as well as a linguistics enthusiast, provided they reason carefully and systematically. What NACLO actually tests is the same analytical capacity that drives success in mathematics, logic, and computer science, applied to the structure of human language. The US record at the IOL reflects this: from 2007 to 2025, US teams won 97 individual medals — 27 gold, more than any other country — and 14 team trophies. IOL selection from the NACLO field places a student among a genuinely elite and unusual group, in a discipline where almost no other pre-college competitive infrastructure exists.

NACLO is the right competition for any high school student with strong analytical reasoning skills and intellectual curiosity about language — the absence of prerequisites is not a lowered bar but a different bar, and the students who excel tend to be exactly the kind of systematic thinkers that selective universities in linguistics, computer science, and cognitive science most want to find.