Guide to the COSMOS Summer Program

So you’re super into exploring bacterial conjugation and antibiotic resistance for tissue engineering. Or maybe the intricacies of animal behavior through the lens of blubber, feathers, and fur. Or maybe smart power systems. Or…

Or some of the other cool things students get to explore in the COSMOS Summer Program.

Great. Because in the guide below, we’ll walk through the California State Summer School for Mathematics and Science (better known COSMOS), including

  • how it works

  • how to apply (and whether it’s worth it)

  • and how it fits into college applications.

Let’s dive in.

What is the COSMOS summer program?

COSMOS is a four-week residential summer STEM program where motivated California high school students dive into advanced topics, work in labs, and get to experience life on a college campus. The program is usually hosted across six different UC schools: UC Davis, UC Irvine, UCLA , UC San Diego, UC Santa Cruz, and UC Merced.

(Useful side note: If you’re planning on applying to the UC Schools, check out this guide to writing your UC application.)

How the COSMOS program works

While living on campus, you join a “cluster” with a group of students who share your interests. Each cluster includes two advanced STEM classes and one science communication course, led by UC professors, researchers, and scientists. 

You’ll spend your time learning through labs, lectures, fieldwork, and team projects. In addition to this, you’ll also complete a research project connected to your cluster topic. (NASA has published past COSMOS student projects, and that’s pretty cool.)

You should also know that the program is pretty selective. Each campus can only accommodate 160-200 students, and a typical COSMOS student has a GPA of 3.5 or higher. 

Also: Living on campus for the entire duration of the program (4 weeks) is a firm requirement, which might be something else that applicants will have to consider. 

History of COSMOS

COSMOS was established by the California Legislature in 1998 (Assembly Bill 2536) to give talented and motivated high school students the opportunity to deepen their interest and skills in STEM through rigorous coursework, hands-on experimentation, and enrichment activities. 

Modeled after the California State Summer School for the Arts, COSMOS was created to provide a similarly immersive academic experience—but focused on science, technology, engineering, and mathematics.

COSMOS launched in 2000, with UC Irvine and UC Santa Cruz as the first campuses to host the program. As demand grew across the state, the UC system expanded COSMOS to additional sites: UC Davis in 2001, UC San Diego in 2004, UC Los Angeles in 2024, and UC Merced soon after.

What do students do in COSMOS?

Each COSMOS Summer Program student chooses a “cluster”—a focused course of study in a specific STEM topic. Cluster topics are different from campus to campus (and year to year), but previous ones include 

just to give you an idea. In your cluster, you might sit for lectures, do some hands-on lab work, collaborate in group projects, go on field trips, participate in workshops, and work on a research project under the guidance of your professor. 

Another aspect of the program is that you get to  live in a dorm with other students for four weeks, where you can experience college residence life and learn how to navigate a dining hall. (Super important collegiate skill.)

So, the overall goal of COSMOS is not just to facilitate a “fun STEM camp,” but to push you academically, help you explore deeper STEM interests, and give you a sense of what a university-level curriculum feels like.

COSMOS eligibility, requirements, and deadlines

Okay, so you’re interested in applying to the COSMOS Summer Program, but want to know what some of the admissions requirements are. We’ve got you. 

Student Eligibility

First and foremost, COSMOS is only open to California high school students. (However, if you’re an eager, non-Californian high school student, you should check out our guide to other summer STEM programs here) 

Applicants can be anywhere from a rising 9th grader (beginning 9th grade in the Fall) through a rising 12th grader (beginning 12th grade in Fall). 

While COSMOS admission does not have a specific GPA requirement, they do report that most admitted students have a GPA of 3.5 or higher. 

Application Details

Filling out an application might seem fairly straightforward, but what else should you be aware of when applying to COSMOS? 

Well, you should know that although six UC schools host their own COSMOS program, you can only apply to one campus. From there, you can rank a 1st and 2nd choice cluster on your application.

You also cannot apply to COSMOS if you have been before, but you can reapply if you’ve applied in the past but haven’t attended (yet). 

Each application requires:

  • A personal statement (about a 350 word limit), plus up to two cluster selection essays (about a 200 word limit each)

  • One teacher recommendation is required, although two recommended (one must be from a STEM teacher)

  • Unofficial high school transcripts 

  • Parent/guardian's e-signature(s) 

  • Application fee

Deadlines (Mark Your Calendar!)

All the action starts when applications open in early January. From there, you have until the deadline (usually in early February) to upload your materials before the submission window ends. 

That means that everything, including your 

  • application materials

  • teacher recommendations

  • parent signatures

  • and your application fee 

must be submitted before this deadline. COSMOS makes it very clear that they offer absolutely no extensions, so you definitely need to hustle during the application window to get everything submitted on time.

How to get into COSMOS

So you know the basics of what each application requires. The next step is figuring out how to make your application shine. Admission to COSMOS Summer Program is selective, so focus on showing genuine curiosity, strong academic preparation, and clear reasons for wanting to join the program. 

To do this, you need to make sure that your application includes:

  • Demonstrated STEM interest and ability.
    This looks like strong grades in math and science classes, enrolling in STEM electives that your school might offer, and any projects or extracurriculars that show your growing commitment to STEM. If you want help translating some of your experiences into an essay format, check out our extracurricular activities essay guide for super helpful tips. 

  • A thoughtful personal statement and strong cluster essays.
    Your essays should explain why you're excited about STEM, what led you here, and why the specific cluster you listed interests you. Remember, you don’t need to be an engineering expert—highlight your curiosity, initiative, and desire to grow. For tips on communicating what academic programs value in applicants, explore what colleges look for in students.

For your shorter cluster essays, try to choose a cluster that genuinely matches your interests and background—not just what sounds impressive. (You’ll also enjoy the program more if you pick subjects that interest you!) In these responses, remember to be specific about how the program will help you grow and what you hope to explore during and after COSMOS.

  • Strong teacher recommendation(s).
    The COSMOS Summer Program has made clear that while only one recommendation is required, two is recommended. (That means you should probably plan on securing two.) One recommendation needs to be from a STEM teacher who can speak to your work ethic, curiosity, collaboration, and potential to thrive in a rigorous academic setting. The other could come from another STEM teacher, a guidance counselor, or any other instructor who you feel can speak to your strengths. 

Oh, and don’t wait until the last minute to ask for these—a good recommendation takes time to write. Your teachers will thank you for a heads up!

How is COSMOS viewed in college applications?

Overall positive, but not the same as free highly selective programs like RSI. (In general, selective free programs are viewed in a stronger light than programs students pay for.)

COSMOS is seen as a well-respected STEM program, especially since it’s run by the UC system and has a competitive admissions process. 

But here’s the thing: colleges don’t value COSMOS alone on college applications. They value what the experience helps you become.

Think of COSMOS as a chance to demonstrate your genuine curiosity, initiative, and depth as a student, not just tally something for your college applications. 

Ideally, through the COSMOS Summer Program you’ll be able to:

  • Really dig into a topic you're excited about

  • Ask questions, explore independently, and challenge yourself

  • Build something, research something, or discover something meaningful

  • Reflect on what the experience taught you and where it’s taking you next

Colleges appreciate students who don’t just attend selective programs, but actively grow, explore, and follow their interests in and beyond them. COSMOS can be one way to expand your interests and demonstrate your commitment to learning—which always looks great on college applications. 

How much does COSMOS cost?

All applicants to the COSMOS Summer Program must submit a non-refundable $46 application fee before the February deadline. Once you’re admitted, the cost of attending this four week residential program is $5,518—this includes housing, meals, all program activities, and field trips. 


Good news: financial aid is available for those who qualify. Applicants are able to ask for aid to cover both the admission fee and tuition, if admitted. 

Is COSMOS worth it?

COSMOS can be a genuinely valuable summer experience, but let's be clear about what it offers. Participating in COSMOS shows colleges you're interested in diving deeper into STEM fields and that you're willing to spend your summer learning. That said, attending COSMOS alone won't be a golden ticket to your dream school.

College admissions officers look at your entire application as a whole, and COSMOS is just one piece of that puzzle. 

For help understanding what colleges care about, check out this guide.

Where COSMOS really shines is in what you'll actually gain from the experience. You'll work on hands-on research projects, connect with professors and peers who share your interests, and get a taste of university-level STEM work. These are the things that can genuinely help you grow—and they might even help you figure out what you actually want to study in college.

If you're only applying because you think seeing "UC-affiliated summer program" will impress admissions officers, then respectfully, you're missing the point. The students who get the most out of COSMOS are the ones who show up genuinely curious and ready to explore STEM topics they care about—not just resume-builders.

 

Natalie Hill is passionate about helping students feel heard, appreciated, and seen through their writing. A former high school teacher, she has taught English, World Geography and Culture, U.S. History, and AP Language and Composition. Since 2017, she has guided hundreds of students through the college application process, helping them achieve their post-secondary goals. An AmeriCorps alumna who served in Chicago’s Near West Side neighborhood and a CEG team member since 2021, Natalie’s goal is for every student to feel valued, loved, and empowered. She lives in Milwaukee, where she enjoys volunteering at a local museum, grabbing a cortado, playing with her kids, and watching Nora Ephron movies.

Top Values: Empathy | Equity | Purpose