COSMOS acceptance rate by cluster | RISE Research
COSMOS acceptance rate by cluster | RISE Research
RISE Research
RISE Research
TL;DR: The COSMOS acceptance rate by cluster varies significantly across the four UC campuses and their individual research clusters. Overall acceptance rates are estimated between 20% and 40%, with the most competitive clusters in biomedical sciences, computer science, and advanced mathematics receiving far more applications than available spots. If you are not accepted, RISE Research is the strongest alternative: a selective 1-on-1 mentorship programme where students publish original research in peer-reviewed journals, with a 90% publication success rate. Our deadline is closing soon.
What Is COSMOS and Who Is It For?
COSMOS (California State Summer School for Mathematics and Science) is a four-week residential programme run across four University of California campuses: UC Davis, UC Irvine, UC San Diego, and UC Santa Cruz. It targets high-achieving students in Grades 8 through 12 who demonstrate exceptional aptitude in STEM subjects.
The programme places students into specialised research clusters, each led by university faculty. Clusters cover fields ranging from astrophysics and robotics to biotechnology and number theory. Students attend lectures, complete lab work, and present a final project at the end of the four weeks.
COSMOS is state-funded and designed specifically for California residents, though a small number of out-of-state students may be considered depending on the campus. The programme costs approximately $2,875 for residential participation, with need-based financial aid available. Full details are available at the official COSMOS programme site.
Understanding the COSMOS acceptance rate by cluster is essential before you apply. Competition is intense, and cluster choice directly affects your odds of admission.
COSMOS Acceptance Rate by Cluster: What the Data Shows
COSMOS does not publish official acceptance rates by cluster. Based on programme capacity and application volume reported by UC campuses, the overall acceptance rate across all clusters and campuses is estimated between 20% and 40%. Individual cluster acceptance rates vary considerably based on available spots and applicant demand.
Each campus offers between six and ten clusters per cohort, with cluster sizes typically ranging from 20 to 25 students. The most oversubscribed clusters consistently include:
Biomedical sciences and biotechnology: High applicant volume across UC San Diego and UC Davis campuses. These clusters attract students with strong biology and chemistry backgrounds and a clear pre-med or research interest.
Computer science, AI, and machine learning: Demand has increased sharply in recent years. UC Irvine and UC San Diego both offer computing-related clusters with limited seats.
Mathematics and number theory: Clusters at UC Santa Cruz in pure and applied mathematics attract students with AMC and AIME experience. These are among the most selective by applicant quality.
Astrophysics and space science: Consistently popular at UC Santa Cruz and UC San Diego, with strong competition from students who already have independent research experience.
Clusters in applied engineering, environmental science, and neuroscience tend to be slightly less oversubscribed, though still competitive. Choosing a cluster that aligns with your strongest academic record and demonstrated interest, rather than the most prestigious-sounding option, is a more effective application strategy.
For a broader look at how selective residential STEM programmes compare, see our full COSMOS programme guide.
How Competitive Is the COSMOS Application?
COSMOS is genuinely selective. Most admitted students carry GPAs above 3.8, have completed advanced coursework in their chosen cluster's subject area, and can demonstrate prior engagement with STEM beyond the classroom. Strong letters of recommendation and a specific, well-articulated statement of purpose are critical components of a competitive application.
The programme receives thousands of applications annually across its four campuses. Cluster-level competition means that applying to a high-demand cluster with a borderline academic profile significantly reduces your odds, even if your overall application is strong.
Applicants who stand out typically have one or more of the following: participation in science fairs or math competitions, prior independent research experience, a published or presented project, or a clear connection between their academic record and the specific cluster they are applying to.
RISE Research produces exactly the kind of verifiable research credential that strengthens a COSMOS application. Students who complete a peer-reviewed publication before applying to COSMOS arrive with an externally validated research record that most applicants cannot match. View the admissions outcomes RISE scholars have achieved to understand what that credential produces.
COSMOS Acceptance Rate by Cluster: How to Choose the Right One
Cluster selection is one of the most consequential decisions in the COSMOS application. Each campus publishes its cluster list annually on its official site. Clusters are not identical across campuses, and the same subject area may be offered at multiple campuses with different faculty, different project formats, and different levels of competition.
A practical approach to cluster selection:
Match your strongest subject to the cluster description. Read the full cluster description, not just the title. A cluster called "Mathematical Modelling" may require programming experience. A cluster called "Bioengineering" may expect prior chemistry lab work.
Research the faculty leading each cluster. If a faculty member's published work aligns with your existing interests or prior projects, name that connection explicitly in your application.
Apply to clusters across multiple campuses if eligible. Students can apply to more than one campus. Spreading applications across campuses with different cluster offerings increases your chances of placement.
Avoid applying to a cluster solely because it sounds impressive. Admissions reviewers can identify mismatched applications. A student with no prior coding experience applying to a machine learning cluster will not present a credible case.
Students who have completed original research through a programme like RISE have a concrete advantage here. A published paper gives you a specific, verifiable project to reference in your cluster application, and it demonstrates the kind of sustained intellectual engagement COSMOS faculty are looking for.
How RISE Research Compares for Students Targeting COSMOS
RISE Research is a selective 1-on-1 mentorship programme where high school students conduct original, university-level research under PhD mentors from Ivy League and Oxbridge institutions. Students produce a peer-reviewed published paper over a 10-week programme, fully online, available to students anywhere in the world.
For students targeting COSMOS, RISE serves two distinct purposes. First, it strengthens your COSMOS application by giving you a verifiable research output to reference. Second, it provides a guaranteed research outcome regardless of whether you are accepted into COSMOS.
The numbers are clear. RISE scholars achieve an 18% acceptance rate to Stanford, compared to 8.7% for the general applicant pool. They achieve a 32% acceptance rate to UPenn, compared to 3.8% for the general pool. RISE carries a 90% publication success rate across 40+ peer-reviewed journals. Every published paper appears directly in the Common App Activities section as an externally verified research credential.
COSMOS produces a programme certificate and a final project presentation. RISE produces a published paper in an independent academic journal. Both are legitimate pathways. RISE provides the more portable and externally verified outcome.
Explore the range of student research projects completed through RISE to see what is achievable across subject areas. Browse our mentor network to find researchers active in the same fields as COSMOS clusters.
Our deadline is closing soon. Book a free Research Assessment to find out what is achievable in your timeline.
RISE Research is open to students targeting COSMOS at any UC campus. Our deadline is closing soon. Book a free Research Assessment to find out what is achievable in your timeline.
What to Do If You Do Not Get Into COSMOS
Rejection from COSMOS is common. With acceptance rates between 20% and 40% overall, and lower rates for the most competitive clusters, the majority of applicants are not accepted. That outcome does not reflect your potential as a researcher or your college application prospects.
RISE Research is the strongest immediate next step. RISE accepts students based on research readiness and genuine intellectual curiosity, not prior programme prestige. The 10-week online format means you can begin original research without waiting for a residential programme. The outcome, a peer-reviewed published paper, is a stronger application signal than a programme certificate because it is independently verified by an academic journal.
For students who want to reapply to COSMOS, completing a RISE research project before the next application cycle gives you a concrete research credential to include in your statement of purpose. That is a meaningful upgrade to any COSMOS application.
For more guidance on what to do after a COSMOS rejection, see our dedicated post: what to do if you did not get into COSMOS.
Other verified alternatives include university-affiliated research programmes at your local UC campus and federally funded science programmes through agencies such as the National Science Foundation. These vary by location and eligibility. RISE is the only option that guarantees a peer-reviewed publication outcome regardless of your location or prior connections.
Frequently Asked Questions About the COSMOS Acceptance Rate by Cluster
What is the overall COSMOS acceptance rate?
COSMOS does not publish an official overall acceptance rate. Estimates based on programme capacity and application volume place the rate between 20% and 40% across all campuses and clusters. The most competitive clusters in computer science, biomedical sciences, and mathematics are likely below 20%.
Each campus sets its own cluster sizes, typically 20 to 25 students per cluster. Total programme capacity across all four campuses is approximately 1,000 students per cycle. Application volume significantly exceeds that number each year.
Which COSMOS cluster is easiest to get into?
No cluster is easy to enter. Clusters in applied environmental science, engineering design, and some interdisciplinary STEM fields tend to receive fewer applications than biomedical or computing clusters, making them relatively less competitive. The right cluster for you is the one that best matches your academic record and demonstrated interest, not the one that appears least popular.
Applying to a cluster where you can point to specific prior work, a class, a project, or an independent study, gives you a stronger application than applying to a high-demand cluster with no relevant background.
Does COSMOS help with college admissions?
COSMOS is a recognised and selective programme, and admission to it signals academic strength. However, the programme itself produces a certificate and a final project, not an externally published paper. Colleges value COSMOS participation as a signal of initiative and STEM ability.
A published research paper, of the kind produced through RISE Research, provides a stronger and more externally verified signal. The two are not mutually exclusive. Many students pursue both. See RISE publications for examples of what students have produced.
Can out-of-state students apply to COSMOS?
COSMOS is a California state programme primarily designed for California residents. Some campuses consider a limited number of out-of-state applicants, but priority is given to California students. International students are generally not eligible. Check the official site for each campus for current eligibility rules, as these can change between cycles.
Students outside California who want a comparable research experience should consider RISE Research, which is fully online and open to students anywhere in the world, with no residency requirement.
What are the best alternatives if I do not get into COSMOS?
RISE Research is the strongest alternative for students who want a verifiable research outcome. RISE produces a peer-reviewed published paper through a 10-week online programme with a 90% publication success rate. That paper appears directly in the Common App Activities section and is independently verified by an academic journal.
Other alternatives include university-affiliated research programmes at local institutions and federally funded STEM initiatives. These vary by location and availability. RISE is the only option that provides a guaranteed published paper outcome with 1-on-1 PhD mentorship, regardless of where you live. Explore recognition RISE scholars have earned alongside their publications.
Conclusion
The COSMOS acceptance rate by cluster is not published officially, but the programme is genuinely competitive. Overall rates fall between 20% and 40%, and the most in-demand clusters in computing, biomedical sciences, and mathematics attract the strongest applicants from across California. Cluster selection, academic alignment, and a demonstrated research record all affect your odds.
RISE Research gives students the research credential that strengthens a COSMOS application and provides a guaranteed published outcome if COSMOS does not work out. With a 90% publication success rate, 1-on-1 PhD mentorship, and admissions outcomes that significantly exceed national averages at top universities, RISE is the most direct path to a verifiable research record for any high school student.
Our deadline is closing soon. If you want a real research outcome on your application regardless of COSMOS results, schedule a free Research Assessment and we will tell you exactly what is achievable in your timeline.
TL;DR: The COSMOS acceptance rate by cluster varies significantly across the four UC campuses and their individual research clusters. Overall acceptance rates are estimated between 20% and 40%, with the most competitive clusters in biomedical sciences, computer science, and advanced mathematics receiving far more applications than available spots. If you are not accepted, RISE Research is the strongest alternative: a selective 1-on-1 mentorship programme where students publish original research in peer-reviewed journals, with a 90% publication success rate. Our deadline is closing soon.
What Is COSMOS and Who Is It For?
COSMOS (California State Summer School for Mathematics and Science) is a four-week residential programme run across four University of California campuses: UC Davis, UC Irvine, UC San Diego, and UC Santa Cruz. It targets high-achieving students in Grades 8 through 12 who demonstrate exceptional aptitude in STEM subjects.
The programme places students into specialised research clusters, each led by university faculty. Clusters cover fields ranging from astrophysics and robotics to biotechnology and number theory. Students attend lectures, complete lab work, and present a final project at the end of the four weeks.
COSMOS is state-funded and designed specifically for California residents, though a small number of out-of-state students may be considered depending on the campus. The programme costs approximately $2,875 for residential participation, with need-based financial aid available. Full details are available at the official COSMOS programme site.
Understanding the COSMOS acceptance rate by cluster is essential before you apply. Competition is intense, and cluster choice directly affects your odds of admission.
COSMOS Acceptance Rate by Cluster: What the Data Shows
COSMOS does not publish official acceptance rates by cluster. Based on programme capacity and application volume reported by UC campuses, the overall acceptance rate across all clusters and campuses is estimated between 20% and 40%. Individual cluster acceptance rates vary considerably based on available spots and applicant demand.
Each campus offers between six and ten clusters per cohort, with cluster sizes typically ranging from 20 to 25 students. The most oversubscribed clusters consistently include:
Biomedical sciences and biotechnology: High applicant volume across UC San Diego and UC Davis campuses. These clusters attract students with strong biology and chemistry backgrounds and a clear pre-med or research interest.
Computer science, AI, and machine learning: Demand has increased sharply in recent years. UC Irvine and UC San Diego both offer computing-related clusters with limited seats.
Mathematics and number theory: Clusters at UC Santa Cruz in pure and applied mathematics attract students with AMC and AIME experience. These are among the most selective by applicant quality.
Astrophysics and space science: Consistently popular at UC Santa Cruz and UC San Diego, with strong competition from students who already have independent research experience.
Clusters in applied engineering, environmental science, and neuroscience tend to be slightly less oversubscribed, though still competitive. Choosing a cluster that aligns with your strongest academic record and demonstrated interest, rather than the most prestigious-sounding option, is a more effective application strategy.
For a broader look at how selective residential STEM programmes compare, see our full COSMOS programme guide.
How Competitive Is the COSMOS Application?
COSMOS is genuinely selective. Most admitted students carry GPAs above 3.8, have completed advanced coursework in their chosen cluster's subject area, and can demonstrate prior engagement with STEM beyond the classroom. Strong letters of recommendation and a specific, well-articulated statement of purpose are critical components of a competitive application.
The programme receives thousands of applications annually across its four campuses. Cluster-level competition means that applying to a high-demand cluster with a borderline academic profile significantly reduces your odds, even if your overall application is strong.
Applicants who stand out typically have one or more of the following: participation in science fairs or math competitions, prior independent research experience, a published or presented project, or a clear connection between their academic record and the specific cluster they are applying to.
RISE Research produces exactly the kind of verifiable research credential that strengthens a COSMOS application. Students who complete a peer-reviewed publication before applying to COSMOS arrive with an externally validated research record that most applicants cannot match. View the admissions outcomes RISE scholars have achieved to understand what that credential produces.
COSMOS Acceptance Rate by Cluster: How to Choose the Right One
Cluster selection is one of the most consequential decisions in the COSMOS application. Each campus publishes its cluster list annually on its official site. Clusters are not identical across campuses, and the same subject area may be offered at multiple campuses with different faculty, different project formats, and different levels of competition.
A practical approach to cluster selection:
Match your strongest subject to the cluster description. Read the full cluster description, not just the title. A cluster called "Mathematical Modelling" may require programming experience. A cluster called "Bioengineering" may expect prior chemistry lab work.
Research the faculty leading each cluster. If a faculty member's published work aligns with your existing interests or prior projects, name that connection explicitly in your application.
Apply to clusters across multiple campuses if eligible. Students can apply to more than one campus. Spreading applications across campuses with different cluster offerings increases your chances of placement.
Avoid applying to a cluster solely because it sounds impressive. Admissions reviewers can identify mismatched applications. A student with no prior coding experience applying to a machine learning cluster will not present a credible case.
Students who have completed original research through a programme like RISE have a concrete advantage here. A published paper gives you a specific, verifiable project to reference in your cluster application, and it demonstrates the kind of sustained intellectual engagement COSMOS faculty are looking for.
How RISE Research Compares for Students Targeting COSMOS
RISE Research is a selective 1-on-1 mentorship programme where high school students conduct original, university-level research under PhD mentors from Ivy League and Oxbridge institutions. Students produce a peer-reviewed published paper over a 10-week programme, fully online, available to students anywhere in the world.
For students targeting COSMOS, RISE serves two distinct purposes. First, it strengthens your COSMOS application by giving you a verifiable research output to reference. Second, it provides a guaranteed research outcome regardless of whether you are accepted into COSMOS.
The numbers are clear. RISE scholars achieve an 18% acceptance rate to Stanford, compared to 8.7% for the general applicant pool. They achieve a 32% acceptance rate to UPenn, compared to 3.8% for the general pool. RISE carries a 90% publication success rate across 40+ peer-reviewed journals. Every published paper appears directly in the Common App Activities section as an externally verified research credential.
COSMOS produces a programme certificate and a final project presentation. RISE produces a published paper in an independent academic journal. Both are legitimate pathways. RISE provides the more portable and externally verified outcome.
Explore the range of student research projects completed through RISE to see what is achievable across subject areas. Browse our mentor network to find researchers active in the same fields as COSMOS clusters.
Our deadline is closing soon. Book a free Research Assessment to find out what is achievable in your timeline.
RISE Research is open to students targeting COSMOS at any UC campus. Our deadline is closing soon. Book a free Research Assessment to find out what is achievable in your timeline.
What to Do If You Do Not Get Into COSMOS
Rejection from COSMOS is common. With acceptance rates between 20% and 40% overall, and lower rates for the most competitive clusters, the majority of applicants are not accepted. That outcome does not reflect your potential as a researcher or your college application prospects.
RISE Research is the strongest immediate next step. RISE accepts students based on research readiness and genuine intellectual curiosity, not prior programme prestige. The 10-week online format means you can begin original research without waiting for a residential programme. The outcome, a peer-reviewed published paper, is a stronger application signal than a programme certificate because it is independently verified by an academic journal.
For students who want to reapply to COSMOS, completing a RISE research project before the next application cycle gives you a concrete research credential to include in your statement of purpose. That is a meaningful upgrade to any COSMOS application.
For more guidance on what to do after a COSMOS rejection, see our dedicated post: what to do if you did not get into COSMOS.
Other verified alternatives include university-affiliated research programmes at your local UC campus and federally funded science programmes through agencies such as the National Science Foundation. These vary by location and eligibility. RISE is the only option that guarantees a peer-reviewed publication outcome regardless of your location or prior connections.
Frequently Asked Questions About the COSMOS Acceptance Rate by Cluster
What is the overall COSMOS acceptance rate?
COSMOS does not publish an official overall acceptance rate. Estimates based on programme capacity and application volume place the rate between 20% and 40% across all campuses and clusters. The most competitive clusters in computer science, biomedical sciences, and mathematics are likely below 20%.
Each campus sets its own cluster sizes, typically 20 to 25 students per cluster. Total programme capacity across all four campuses is approximately 1,000 students per cycle. Application volume significantly exceeds that number each year.
Which COSMOS cluster is easiest to get into?
No cluster is easy to enter. Clusters in applied environmental science, engineering design, and some interdisciplinary STEM fields tend to receive fewer applications than biomedical or computing clusters, making them relatively less competitive. The right cluster for you is the one that best matches your academic record and demonstrated interest, not the one that appears least popular.
Applying to a cluster where you can point to specific prior work, a class, a project, or an independent study, gives you a stronger application than applying to a high-demand cluster with no relevant background.
Does COSMOS help with college admissions?
COSMOS is a recognised and selective programme, and admission to it signals academic strength. However, the programme itself produces a certificate and a final project, not an externally published paper. Colleges value COSMOS participation as a signal of initiative and STEM ability.
A published research paper, of the kind produced through RISE Research, provides a stronger and more externally verified signal. The two are not mutually exclusive. Many students pursue both. See RISE publications for examples of what students have produced.
Can out-of-state students apply to COSMOS?
COSMOS is a California state programme primarily designed for California residents. Some campuses consider a limited number of out-of-state applicants, but priority is given to California students. International students are generally not eligible. Check the official site for each campus for current eligibility rules, as these can change between cycles.
Students outside California who want a comparable research experience should consider RISE Research, which is fully online and open to students anywhere in the world, with no residency requirement.
What are the best alternatives if I do not get into COSMOS?
RISE Research is the strongest alternative for students who want a verifiable research outcome. RISE produces a peer-reviewed published paper through a 10-week online programme with a 90% publication success rate. That paper appears directly in the Common App Activities section and is independently verified by an academic journal.
Other alternatives include university-affiliated research programmes at local institutions and federally funded STEM initiatives. These vary by location and availability. RISE is the only option that provides a guaranteed published paper outcome with 1-on-1 PhD mentorship, regardless of where you live. Explore recognition RISE scholars have earned alongside their publications.
Conclusion
The COSMOS acceptance rate by cluster is not published officially, but the programme is genuinely competitive. Overall rates fall between 20% and 40%, and the most in-demand clusters in computing, biomedical sciences, and mathematics attract the strongest applicants from across California. Cluster selection, academic alignment, and a demonstrated research record all affect your odds.
RISE Research gives students the research credential that strengthens a COSMOS application and provides a guaranteed published outcome if COSMOS does not work out. With a 90% publication success rate, 1-on-1 PhD mentorship, and admissions outcomes that significantly exceed national averages at top universities, RISE is the most direct path to a verifiable research record for any high school student.
Our deadline is closing soon. If you want a real research outcome on your application regardless of COSMOS results, schedule a free Research Assessment and we will tell you exactly what is achievable in your timeline.
Summer 2026 Cohort III Deadline Closing on 25th July
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