| Application deadline | Unconfirmed — check official site | Unconfirmed — check official site | Unconfirmed — check official site |
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| Cost | Last year's cycle (2026): $5,518; 2027: Unconfirmed — check official site | Unconfirmed — check official site | Unconfirmed — check official site |
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| Financial aid | 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 | Last year's cycle (2026): U.S. family-income guarantee: Amount: Unconfirmed — check official site. U.S. students from families under $80,000 attended free in 2026.; Full/partial need-based aid and international aid: Amount: Unconfirmed — check official site. Aid available where cost is a barrier; international aid considered case by case.; 2027: Unconfirmed — check official site |
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| Expenses and aid conditions | 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 | Last year's cycle (2026): U.S. family-income guarantee: Amount: Unconfirmed — check official site. U.S. students from families under $80,000 attended free in 2026.; Full/partial need-based aid and international aid: Amount: Unconfirmed — check official site. Aid available where cost is a barrier; international aid considered case by case.; 2027: Unconfirmed — check official site |
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| Stipend or pay | Unconfirmed — check official site | Last year's cycle (2026): 2026 Summer I or Summer II fellowship: $4,000; 2027: Unconfirmed — check official site | Unconfirmed — check official site |
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| Eligibility | Grades 9–12 (provider uses rising grades) | Grades 10–12 when applying; check the provider's rules for graduating seniors | Grades 10–12; Grade timing: Unconfirmed — check official site |
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| Additional eligibility | 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 | Ages 14–18; Residency: Students from the United States and abroad are eligible; international financial aid is case by case; Requirement: Be age 14-18 by the applicable program cutoff; Requirement: Have completed grade 9 or equivalent before the session; Requirement: Not be enrolled full time in a college or university by the program's first day; Requirement: Be available for the entire six-week residential session and comply with dormitory, curfew, visiting, safeguarding, and conduct rules; Requirement: Independently attempt the official application problem set and explain experiments, conjectures, proofs, and partial progress; Requirement: Submit the required recommendation, transcript, form, short answers, and any financial-aid documents; Requirement: Retain scratch work and be prepared to explain reasoning if originality is verified; Exclusion: Applicants outside the age/education window or already full-time college students at program start; Exclusion: Collaborative, copied, AI-assisted, internet-generated, uncited, or inadequately explained problem-set work; Exclusion: Applicants unable to reside for the full six weeks or follow residential/safety expectations; Exclusion: Assuming all eight problems must be solved or that prior advanced courses/research are required; Exclusion: Assuming selection guarantees aid, publication, conference presentation, college credit, recommendation, admission advantage, internship, or job |
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| Session dates or duration | Catalog terms: 4 weeks; 2027: Unconfirmed — check official site | Catalog terms: 8–10 weeks; 2027: Unconfirmed — check official site | Catalog terms: 6 weeks; 2027: Unconfirmed — check official site |
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| Format | In person | Hybrid | In person |
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| Housing and supervision | Residential. Supervision and housing details: Unconfirmed — check official site | Non-residential. Supervision and housing details: Unconfirmed — check official site | Residential. Supervision and housing details: Unconfirmed — check official site |
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| Location | 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 | Boston, Boston University campus, Massachusetts |
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| Selection and application | 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. | Selection: About 80 high-school students are selected through demonstrated mathematical thinking in the problem set, academic context, recommendation, transcript, and short answers. PROMYS does not publish the current applicant count or acceptance rate. Application materials: One recommendation |
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| Official sources | 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 | Source 1 · checked 2026-08-20Source 2 · checked 2026-08-20Source 3 · checked 2026-08-20Source 4 · checked 2026-08-20Source 5 · checked 2026-08-20Source 6 · checked 2026-08-20 |
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