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California State Summer School for Mathematics and ScienceCOSMOS

COSMOS is a four-week residential STEM program created by the California Legislature and run by the University of California at six campuses, including UC Irvine, for California students only. UC's report to the Legislature shows that 22% of 4,833 complete applications were admitted in 2019.

Any status, must study in the US
California students only
Tuition · aid available

Plan your summer program applications Official website ↗

Size and selectivity22% admitted (2019)

Photo: Mikhail Nilov / Pexels

Eligibility: Any status, must study in the US · California students only
Cost: Tuition · aid available
Latest deadline: Feb 5, 2027

COSMOS at a Glance

Host: Created by the California Legislature in 1998 (AB 2536) and run by the University of California at six UC campuses
Field: Advanced STEM topics taught in clusters by UC faculty, spanning engineering, biomedical science, physics, computer science and mathematics
Grades and age: Students entering grades 9 through 12 in fall 2027, that is, 8th through 11th graders in 2026-27; 8th-grade applicants also submit their 7th-grade report card
Citizenship and residency: Open only to students attending high school in California; out-of-state and international students cannot apply. The statewide policy says all students attending high school in person in California are eligible, and the site lists no citizenship or green card requirement; individual cases are interpreted by the COSMOS Statewide Office. Students who have attended COSMOS before cannot apply again.
Cost: The four-week residential program costs $5,793 for 2027 ($5,518 in 2026), covering housing, meals, orientation, field trips and activities; payments are non-refundable. The application fee is also non-refundable: $46 in 2026, while the 2027 dates page shows both $48 and $46, so confirm on the official site when paying; fee waivers are available. Need-based financial aid depends on each year's fundraising, with no guaranteed amount or percentage; students offered full aid pay a $200 deposit that is refunded after they complete the program.
Dates and format: Four weeks, fully residential; every student must live on the campus that admits them. The six sites are UC Davis, UC Irvine, UCLA, UC Merced, UC San Diego and UC Santa Cruz. The 2026 UCI session ran July 5 to July 31; 2027 dates have not been announced. The UCI site notes that the program gives no credit, exams or grades.
Application dates: The 2027 application opens at 8:00 am on January 6, 2027 and closes at 11:59 pm on February 5 (help desk support ends at 5:00 pm); mailed items and the optional financial aid application must be postmarked by February 6. Decisions are released March 25, 2027; admitted students accept and pay one-third of the cost by April 7 and the balance by April 16. The last waitlist offers go out May 26.
Application materials: Online application with a personal statement, plus a cluster choice essay; at least one recommendation, which must come from a STEM teacher, with a second (from a counselor or other academic recommender) strongly recommended. Recommendations are online questionnaires, not formal letters. Also required: an unofficial transcript generated after the application opens, a parent or guardian e-signature and the application fee. SAT and ACT scores are not considered. Each student applies to one campus and lists a first- and second-choice cluster.
Size and selectivity: The COSMOS homepage says each campus can accommodate about 150 to 250 participants (the program overview page says 160 to 200; check the official site), selection is competitive, and a typical student has a GPA of 3.5 or above. UC's March 2021 report to the Legislature states that of 4,833 completed applications for summer 2019, 1,060 (22%) were admitted and 340 (7%) were wait-listed; the UCI site had 186 participants that year. No admission rate has been published since 2019.

Verified against official pages on 2026-10-06 · cosmos-ucop.ucdavis.edu

About COSMOS

COSMOS was created by the California Legislature in 1998 and is run by the University of California as a four-week residential STEM program for California students. Applicants choose one of six campuses (UC Davis, UC Irvine, UCLA, UC Merced, UC San Diego and UC Santa Cruz) and join a cluster in which UC faculty lead classes, labs and projects. The UC Irvine site held its first session in 2000 and offered 8 clusters in 2026, including data science in the biomedical sciences, physics and big data computation, sustainable aviation systems, and brainwave bioengineering.

Admission to COSMOS is competitive. The homepage says each campus can accommodate about 150 to 250 participants (the program overview page says 160 to 200) and that a typical student has a GPA of 3.5 or above. UC’s 2021 report to the Legislature shows 4,833 completed applications for 2019, with 1,060 (22%) admitted. The program charges $5,793 for 2027, with need-based aid available. Eligibility depends on attending high school in person in California, and the site lists no citizenship requirement.

For Irvine families, COSMOS is close to home, competes only among California students and accepts applications from 8th grade. It gives no credit or grades; what students gain is cluster project experience and guidance from UC faculty, which can go on the activities list of a college application. EDUBUS suggests treating COSMOS as a step in STEM before applying to national programs such as RSI and SSP.

How to Apply to COSMOS

Each student may apply to only one campus and two clusters, and cluster prerequisites differ. Read the cluster descriptions for your target campus before the application opens in January, then choose a first and second choice.
The recommendation must come from a STEM teacher and is due with the application on February 5, 2027. Ask your recommender before winter break, and ask them to whitelist COSMOS emails so district spam filters do not block the request.
COSMOS does not consider SAT or ACT scores. The UCI site lists math and science grades, math or science teacher recommendations and the personal statement as its admission factors; the statement should describe specific projects and explain the choice of cluster.

Application Support for COSMOS

EDUBUS starts with an assessment of grades, competitions and research, then decides which programs to aim for and which to hold as back-ups. We then guide each application form, essay, qualifying problem set and interview, and help turn the summer into part of the college application.

Plan your summer program applications About our summer program service →

FeatureSummer Programs Recommended by MIT AdmissionsMIT Admissions lists 23 selective summer programs on its website. Each one is in this library, with eligibility, cost and selectivity.

COSMOS: Frequently Asked Questions

Can an Irvine student admitted to the UC Irvine site commute from home?

No. COSMOS requires every student to live on the campus that admits them for all four weeks, as residential life is part of the program. The 2026 UCI session ran July 5 to July 31, and students who live nearby also move into the dorms.

Can a student attending high school in Irvine on a student visa apply to COSMOS?

Two parts of the site need to be read together. The statewide policy says all students attending high school in person in California may apply and lists no citizenship or green card requirement, while the FAQ says international students cannot apply. A visa holder at a California high school falls under the individual cases the policy says need interpretation, so confirm in writing with the COSMOS Statewide Office before applying.

How much does COSMOS cost in total?

The four-week residential program costs $5,793 for 2027, including housing, meals and activities, plus a non-refundable application fee ($46 in 2026). Financial aid is assessed on family income and size, with no guaranteed percentage, and the result arrives with the admission decision. Applying for aid does not affect admission.

How early can an Irvine middle school student apply to COSMOS?

Students can apply in 8th grade for the summer before 9th grade. Each student may attend COSMOS only once, and those not admitted may reapply. EDUBUS suggests timing the application to the cluster prerequisites and waiting until 9th or 10th grade if the core math and science courses are not yet done.

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Sources12 sources · checked 2026-10-06

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