| Application deadline | Unconfirmed — check official site | Unconfirmed — check official site | Unconfirmed — check official site |
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| Cost | Last year's cycle (2026): $1,695–$2,195; 2027: Unconfirmed — check official site | Last year's cycle (2026): $5,518; 2027: Unconfirmed — check official site | Unconfirmed — check official site |
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| Financial aid | Last year's cycle (2026): 2026 qualifying competition-achievement discount: $100. One $100 completion-paid discount with proof for specified MATHCOUNTS National, USAJMO or USAMO achievements.; 2027: Unconfirmed — check official site | Last year's cycle (2026): 2026 need-based application and program assistance: Up to $5,564. Could assist with the $46 application fee and $5,518 program cost based on family income, family size and available funds; actual award not guaranteed.; 2027: Unconfirmed — check official site | Unconfirmed — check official site |
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| Expenses and aid conditions | Last year's cycle (2026): 2026 standard online placement test: $50–$100. Students not recently enrolled generally tested; scheduled-session fee rose closer to summer and was nonrefundable and nontransferable. A special session could cost $150.; 2026 qualifying competition-achievement discount: $100. One $100 completion-paid discount with proof for specified MATHCOUNTS National, USAJMO or USAMO achievements.; 2027: Unconfirmed — check official site | Last year's cycle (2026): 2026 COSMOS application fee: $46. Nonrefundable; pending fee-waiver review could change when or whether payment was required.; Credit-card transaction fee on program payments: Amount: Unconfirmed — check official site. Approximately 2.5% when paying program costs by credit card; application fee exempt.; 2026 need-based application and program assistance: Up to $5,564. Could assist with the $46 application fee and $5,518 program cost based on family income, family size and available funds; actual award not guaranteed.; Full-financial-aid attendance deposit: $200. Required only for admitted students offered full aid and refunded to the legal guardian after successful completion.; 2027: Unconfirmed — check official site | Unconfirmed — check official site |
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| Stipend or pay | Unconfirmed — check official site | Unconfirmed — check official site | Last year's cycle (2026): 2026 Summer I or Summer II fellowship: $4,000; 2027: Unconfirmed — check official site |
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| Eligibility | Grades 4–12; Grade timing: Unconfirmed — check official site | Grades 9–12 (provider uses rising grades) | Grades 10–12 when applying; check the provider's rules for graduating seniors |
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| Additional eligibility | Requirement: Be a rising fourth- through twelfth-grader for Math Challenges or a seventh- through twelfth-grader for Advanced Studies; Requirement: Provide accurate age, grade, math-course and official contest-score history; Requirement: Take an assigned placement test unless exempt as a recent IDEA MATH student; Requirement: Accept the academic team's final course placement; Requirement: Attend all live Eastern-time Zoom classes with camera and microphone on; Requirement: Complete homework and present mathematical solutions in class; Exclusion: The two summer tracks have different grade ranges, dates, course levels and prices; Exclusion: Registration alone does not complete enrollment; tuition must be paid in full; Exclusion: A preferred course is not guaranteed because placement, enrollment, staffing and capacity control offerings; Exclusion: Only enrolled students may enter the live Zoom classroom, and recording or photography is prohibited | Residency: Attend high school in person in California; Requirement: Be rising into grade 9, 10, 11 or 12 for the program fall year; Requirement: Attend high school in person in California; Requirement: Demonstrate academic excellence and preparation for the selected STEM cluster; Requirement: Complete cluster-specific course prerequisites; Requirement: Live on the host UC campus for the full program; Requirement: Be a first-time COSMOS participant; Exclusion: Students not attending a California high school in person; Exclusion: Students who previously attended any COSMOS program; Exclusion: Applicants outside the rising-grade 9-12 range; Exclusion: Applicants unable to live on campus for the full program; Exclusion: Late application, supporting, payment or admission materials; Exclusion: Assuming a 3.5 GPA is an absolute statewide minimum rather than the published typical profile | Residency: Must be able to participate at an available Project SEED site or eligible virtual project; in-person site selection considers a safe daily commute; Requirement: Document household annual income at or below 300% of applicable Federal Poverty Guidelines; Requirement: Provide an accepted tax, free/reduced-lunch, SNAP/WIC, TRIO, or SAT/ACT fee-waiver eligibility document; Requirement: Preferably be a current high-school sophomore, junior, or senior; the 2026 cycle also allowed graduating seniors; Requirement: Have completed at least one high-school chemistry course and demonstrate interest in science or chemistry; Requirement: Obtain parent/guardian permission if under 18; Requirement: Be available for the full project, normally at least eight weeks and about 40 hours weekly for in-person research; Requirement: Meet the local site's commute, safety, lab, onboarding, and schedule requirements; Exclusion: Applicants who cannot document the financial-eligibility requirement; Exclusion: Applicants without completed high-school chemistry; Exclusion: Applicants unable to commit to the selected site's full schedule or safely commute for an in-person placement; Exclusion: Assuming prior lab experience is required or guarantees selection; Exclusion: Assuming application guarantees a placement, preferred lab, virtual option, $4,000 next-cycle amount, conference trip, publication, college credit, recommendation, scholarship, admission advantage, or job |
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| Session dates or duration | Last year's cycle (2026): Starts June 28, 2026; Ends August 11, 2026; 5–6.43 weeks; 2027: Unconfirmed — check official site | Catalog terms: 4 weeks; 2027: Unconfirmed — check official site | Catalog terms: 8–10 weeks; 2027: Unconfirmed — check official site |
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| Format | Online | In person | Hybrid |
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| Housing and supervision | Non-residential. Supervision and housing details: Unconfirmed — check official site | Residential. Supervision and housing details: Unconfirmed — check official site | Non-residential. Supervision and housing details: Unconfirmed — check official site |
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| Location | Live online in U.S. Eastern Time | Davis, California, Irvine, California, Los Angeles, California, Merced, California, San Diego, California, Santa Cruz, California, UC Davis, UC Irvine, UCLA, UC Merced, UC San Diego, UC Santa Cruz | Participating university, government, and industry research sites; virtual projects may also be offered |
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| Selection and application | Selection: Placement is academic and capacity-limited rather than governed by a published acceptance rate. Likely class sizes were 6-12 in early prealgebra levels and 6-16 in others, with stated caps of 16 or 20. | Selection: Each of six campuses accommodates roughly 160-200 students, and clusters typically enroll 20-25 with a commonly reported 5:1 student-to-faculty ratio. Admissions are competitive and based on academic merit relative to the selected topic, but applicant count and statewide acceptance rate were not published. Application materials: One personal statement; One required teacher recommendation, with two recommended | Selection: Local coordinators select among financially and academically eligible applicants based on performance, science interest, full-summer availability, site capacity/budget, safe commute, and mentor/project fit. ACS publishes no single current acceptance rate. |
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| Official sources | Source 1 · checked 2026-08-22Source 2 · checked 2026-08-22Source 3 · checked 2026-08-20 | Source 1 · checked 2026-08-22Source 2 · checked 2026-08-22Source 3 · checked 2026-08-22Source 4 · checked 2026-08-22Source 5 · checked 2026-08-22Source 6 · checked 2026-08-22Source 7 · checked 2026-08-20 | Source 1 · checked 2026-08-20Source 2 · checked 2026-08-20Source 3 · checked 2026-08-20 |
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