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The pipeline opens with the Local Section Exam, a 60-question multiple-choice test administered each March through ACS Local Sections — free to enter, open to all US high school students in grades 9–12. US citizenship or permanent residency is required to advance beyond the local level. Each ACS section nominates its top performers to the National Exam, with no more than two students per high school permitted — a cap that adds meaningful selectivity at the school level. The National Exam, administered in April, consists of three parts: 60 multiple-choice questions covering the full scope of advanced chemistry, a free-response section, and a laboratory practical in which students complete two hands-on experiments — chromatography, titration, or qualitative analysis — in 90 minutes. The top 20 scorers nationally are invited to the two-week Study Camp at the University of Maryland, where students receive advanced instruction from leading chemistry educators and are tested in both theoretical and laboratory formats; the four highest performers form the US IChO team. The 2025 US team won four gold medals at the 57th IChO in Dubai, UAE.

The lab practical component is the detail that most distinguishes the USNCO from purely written science competitions — a student who advances to the National Exam has demonstrated not just conceptual chemistry knowledge but the ability to execute experimental technique under timed, competitive conditions. Study Camp selection, reaching the top 20 in the country from a field of 10,000, is a genuinely elite credential. IChO team membership carries the same admissions weight as any International Science Olympiad representation: MIT, Caltech, and peer research universities treat it as one of the most significant pre-college STEM credentials available, in a discipline where the preparation required goes well beyond AP Chemistry into university-level physical, organic, and analytical chemistry.

The USNCO is the right competition for a high school student with serious interest in chemistry who is ready to go significantly beyond AP — the National Exam draws on content that most undergraduates encounter in their second year, and the students who reach Study Camp have typically spent years building toward this goal.