How to Write the Caltech Supplemental Essays: Examples + Guide 2026/2027

Last Updated on 08/26/2026 by Ethan Sawyer

If you’ve ever thought to yourself, “You know, I think I’m really looking for a school that teaches students how to launch eggs using trebuchets,” then you should probably take a look at Caltech.

Well known for its strong science and engineering programs, nestled below the San Gabriel mountains near Pasadena, and linked to the Jet Propulsion Laboratory, Caltech offers aspiring STEM students a fun, beautiful place to build a foundation for their future careers.

Because of that, Caltech is a very selective school, and you’ll want to spend a good amount of time developing strong responses to its supplemental essays. To explore how, check out the guide below.

If you want to get a clearer sense of what Caltech is looking for, you can explore an extensive, by-the-numbers look at its offerings, from enrollment and tuition statistics to student life and financial aid information, on its Common Data Set. 

And a note that Caltech is pretty clear and direct about what it looks for in essays and what it looks for in students.

This is a classic “Why Major” essay.  You’ll find a step-by-step guide to writing this essay at this link, but here’s the short version:

Step #1: Imagine a mini-movie of the moments that led you to your interest in STEM and create a simple, bullet point outline.*

Step #2: Put your moments (aka the “scenes” of your mini-movie) in chronological order, as it’ll help you see how your interests developed. It also makes it easier to write transitions.

Step #3: Decide if you want to include a specific thesis that explicitly states your central argument-in this case what you want to study and why. This thesis can be at the beginning, middle, or end of your essay.

Step #4: Write a draft!

Important note before writing your response: When choosing your mini-moments, note that there’s potential for overlap in your answers to some of the other Caltech prompts, so consider carefully which experiences you’ll focus on for each prompt to avoid redundancy in your answers. Since this is Caltech, with an obvious emphasis on… tech, it’s possible the prompts were designed this way to urge you to show depth and diversity in your STEM interests and experiences.

Here’s a great example (written for another school but also applicable here).

Example:

I fell in love with computers at nine when I learned how to make a graphical turtle crawl across the screen, and I’ve written code every week since. I am self-taught in nine programming languages (my favorite is C++), which I learned through iteration and persistence. Teaching advanced algorithms at a programming bootcamp for the past two years allowed me to share my love of computer science with others.

My interest in CS runs deep-from studying memory virtualization to the beauty of the B-Tree O(log n) search algorithm. Writing protein folding simulations for my biology teacher peaked my interest in computational science. Building real-world machine learning models during each of the last two summers expanded my awareness of the types of problems computers can help solve.

Over the years, though, I have shaped a focus: security. In the process of running multiple servers, developing custom security software, and configuring the switching and routing for a 96-computer network, I became fascinated with the challenge of creating secure systems. Software has found its way into all aspects of our lives, creating staggering risks to privacy and security. These are problems I want to study, understand, and solve. (196 words)

Tips + Analysis

1. Take the reader on your journey. Did you feel the author practically grab your hand and pull you along the exhilarating ride of their lifelong love affair with computers? Each paragraph is chock full of the myriad ways they’ve engaged with their object of desire. You get a great picture of the student’s skills and accomplishment, as well as their self-motivated pursuit of their passion.

2. Let your geek flag fly. This writer exudes about memory virtualization and the B-Tree O(log n) search algorithm, knowing they’re talking to leaders in the field (and who knows, potentially future collaborators!). Knowledge of specialized language is a great way to demonstrate fit to major, so feel free to use lingo as you normally would to show you know your stuff.

3. Share why you care. This essay isn’t just a list of all the things the student has done. It’s a reflection of why computers matter to them and what they plan to do with them. You hear that they value sharing knowledge with others and see themselves using computers to solve real-world problems. Find those “mini-movie moments” to show how you’ve fallen in love with your field of interest over time.

4. Look ahead. “Why Major” essays are the natural place to talk about potential future careers, if you know what you want to pursue. Even if you don’t know yet, you can still end the essay by looking forward to how the major you’re interested in will prepare you for life after college.

Option (a): Collaboration

The prompt offers four possible frames/approaches: you needed help, you offered help, you changed your thinking through collaboration, or you contributed to someone else’s understanding. 

Pick one (and if your topic happens to hit another, great). But trying to do all four in 200 words produces a blur.

A note to address possible student worries: “I needed help” is the underrated one. Most students reach for “I taught someone,” because teaching sounds generous and competent. But Caltech’s own framing—work through difficulty, contribute to one another’s understanding—suggests they’re also very interested in students who can be taught, and who understand how to ask for help and practice self-care. 

At a school where the core curriculum is famously punishing and collaboration on problem sets is the norm rather than the exception, “here’s the moment someone unlocked something for me, and here’s what I did with it” can be genuinely compelling (not to mention offering some nice potential for vulnerability). It’s also probably a much less crowded lane.

And keep in mind a big part of what they’re looking to see here is the second question: What did that experience teach you about learning and working with others? That’s roughly 40% of the prompt, and it’s the part students skip when they run low on words. As you brainstorm and outline, be sure to budget for it.

Tips for drafting

1. Name the actual moment the thinking changed. The whole essay hinges on a before and an after. What did you believe about the problem at 3pm, what did someone say, and what did you believe at 3:15? What obstacle were you facing, how exactly did you seek help, and how did that help shift you?
2. Let someone else be smart. One easy way to potentially go wrong here is the common group-project essay where the writer quietly did all the work while everyone else flaked. That’s a real experience and it may even be true, but it answers the opposite of what’s being asked. If your collaborator only exists in the essay as an obstacle, pick a different story.
3. Keep actual STEM in it. “We disagreed about the approach” is pretty vague. What was the problem? What was the misunderstanding? Was it a sign error, a flawed assumption about the sample, a disagreement about which model applied? Specificity is what separates this from a generic teamwork essay.
4. Answer the second question explicitly. Don’t imply the lesson—state it (or better, a few, with layers). And push past “collaboration is important.” What do you now believe about how understanding actually gets built between people? How did this experience level you up?

Option (b): Process

Here’s a great line to hone in on: What would you still defend about your process, regardless of the outcome?

Caltech is telling you, out loud, very clearly, that the thing doesn’t have to have worked.

And even though some students have a (misguided) fear of writing about times they failed, there’s a great opportunity here: You can generally show far more growth from times you failed than times you succeeded. (And a big part of STEM is failing, and learning, and iterating.)

The experiment that produced garbage data, the model that never converged, the build that failed at the deadline—all fair game, as long as you can articulate why your approach was sound anyway.

A structure that tends to work:

• What the problem was, and why it was hard (probably fast—like two or three sentences)
• Where the uncertainty hit—the specific fork where you didn’t know what to do
• What you did and why you chose it
• What you’d still defend

That third bullet is probably where most of your word count should go (the fourth is probably second most, to get into insights/growth), and it’s where you should get technical. “I tried a different approach” isn’t really gonna work here. “I switched from brute-force recursion to memoization once I noticed the call tree was recomputing the same subproblems” helps us see the depth you’re getting into.

Tips for drafting

1. Pick a problem where you got stuck. Reread the prompt: Stuck is the assignment. If the story is “it was hard, and then I worked hard, and then it worked,” there’s no uncertainty in it and your essay probably has nothing to grab.
2. Show the reasoning in real time. There’s a big difference between “I learned to be systematic” and “I started changing one variable per run because I couldn’t tell which of the three fixes had actually done anything.” The second one shows the thinking; the first one summarizes it away.
3. Land on a principle, not a moral. “Regardless of the outcome” wants something you’d carry into the next problem: check the assumption before you scale it, build the ugliest working version first, keep the failed runs. Concrete, portable, arguable. Not “never give up.” (Sure, generally don’t give up, though sometimes it’s fine or even beneficial to do so, but it’s not exactly a deep learning.)
4. Don’t apologize for the result. If it failed, say so plainly and move on. Students who spend three sentences softening the failure lose the words they needed for the actual interesting part.

Because these prompts are new, we don’t have any essays that address their specific focus

Here’s a fun chance to celebrate your nerdy side.

Are you a student that gets so excited talking or thinking about photovoltaic efficiency that you don’t even notice the sun going down?

Great. Here’s your chance to dive in and show us.

Caltech wants a bright, curious, independent student body. It’s looking for intellectual vitality, and this essay is your opportunity to show that side of yourself. 

So what about STEM gets you fired up and why? 

You can talk about one of those school or pet projects that you just can’t get enough of, that make your mind spin about the big questions and dream up the answers. Think about things that have inspired you to go down research rabbit holes, that have motivated you to take action, or that have enhanced your understanding of a subject. Choose experiences that genuinely pique your curiosity. Don’t pick something just because you think Caltech will like it. Genuine interest is both easy to write about and hard to fake! 

And a note that while they do directly say “be as specific or broad as you would like,” writing well and being broad can be difficult to do simultaneously. You can try if you want. But we’ve generally found that picking something specific that gets you excited and curious is easier to build an essay around.

Finally, pay careful attention to the specific questions in whatever prompt you choose. For example, it’s easy to skip over some of “What drew you to it, how have you pursued it, and what do you still want to understand?”, but try to choose a topic that allows you to hit all three.

Check out this example, about one high school experience.

Example:

In my ROP Manufacturing Engineering Technology Course, I’m learning about the application of math in manufacturing. We’ve worked on isometrics, including drawing the different views of a 3D object and solving the missing dimensions. Now, I’ve begun learning g-code for CNC mill programming: first linear interpolation then circular interpolation. I’ve loved thinking through what a machine would do step by step, and I feel great accomplishment when my program finally runs correctly. I wrote a program to carve out my own design of a camera with a heart in the lens. Currently, I’m learning Mastercam CAD/CAM software. I can’t wait to take the Advanced course in the Spring semester to further pursue engineering fundamentals. (115 words)

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Tips + Analysis

1. Focus on clarity and specificity. While hooks can be great, you’ll want to be pretty stingy with your word count for this essay. The above example dives straight in, clearly setting up the experience for the reader with the first lines (and using the specificity of the experience to be a little hook-like). Then, it gets into some nice, specific detail regarding what the student did, and why the experience matters. Notice how much the language focuses on clarity and detail.
2. Show your chops. This example shows the student doing some higher-level STEM work. It gets into complex, interesting experiences in a (focused) range of areas, using language that may not mean much to the average reader but that shows they’ve already started developing the scientific chops they’ll need at Caltech.
3. Connect to your values through reflection. We refer to this as the “so what” element of the essay—above, some of the word count toward the end is devoted to helping the reader understand why this experience was meaningful. This reflection on meaning is something that the essay above has, and could have done even more so with some of the remaining word count. Be sure to spend some time exploring why the details and experiences you’ve discussed connect to some of your core values by reflecting on what they’ll allow you to pursue or explore, and why those things matter to you. Consider linking to specific, dynamic problems you’re interested in working on.

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Here’s a bonus essay we love, written for another school, but a great example of how to repurpose other essays to fit multiple prompts with your college applications. 

Example: 

At the Biotechnology Open House at Santiago Canyon College, I participated in gel electrophoresis, separating red, blue, and purple dyes by running current through the gel with the buffer solution. The purple dye separated into two bands of blue and red. Observing that the red moved farther than the blue, I concluded that the molecules were smaller and moved through the gel quicker. After learning that electrophoresis is even used to separate DNA, I had the opportunity to extract DNA from my cheek cells. I was amazed to see my own genetic blueprint in a tube! These experiments excited me to learn more about how biology and engineering can create pharmaceutical, diagnostic, and environmental products to benefit society. (118 words)

How to write Caltech Supplemental Essay Prompt #4

You can think of this as Caltech’s version of a “contribute” prompt. Some schools want to know how, based on your experiences, you’d contribute to their campuses. 

The key here is to 

1. a) share some experiences you’ve already been a part of and what you’ve learned from them, then 
2. b) connect these experiences to particular opportunities available on their campus. 

Help the admission officer reading your application visualize you at their school.

For a fuller “How will you contribute” guide + examples with analysis, check out that link, but here’s the short version. 

Essentially, a way to think of this kind of prompt is that it’s a combo of “community/identity/background” and “why us” prompts: Use some of your response to show how you’ve become who you are, and then show how those experiences shape what you will bring to the college through linking to specific opportunities/groups/details. Connect your unique upbringing, in a very broad sense of the word, with what the school offers and how you will make a great team.

For the Caltech version, you can keep it STEM focused (since Caltech has said in the past that you generally can’t get to STEM-y for them), or potentially use it to show them a side they aren’t seeing yet.

STEP 1: BRAINSTORM (ALL ABOUT YOU).

Do the “If You Really, Really Knew Me” Exercise.

STEP 2: RESEARCH THE COLLEGE (LEARN ALL ABOUT THEM).

Make a copy of the “Why us” Essay Chart 2.0, research the school you’re writing your essay for, and fill in the first two columns.

Once you’ve done these exercises, you’ll have a better sense of: 

• YOU: A bunch of different values/talents/skills/identities/qualities/insights that you’ll bring to a college campus, and
• THEM: A variety of programs/courses/clubs/affinity groups that your college offers.

STEP 3: CONNECT YOU… TO THEM (I.E., THE COLLEGE YOU’RE APPLYING TO). 

Make connections between what the school offers and what you’re interested in.

Here’s an example essay written for a different schools “contribute” prompt:

Aside from my inherent love for bagels, my Jewish background has led me to become more embedded in my community, joining Jewish activists and building a website on Holocaust education.

In the 1930s, 36 members of my family were lost to the Holocaust, and that fact has led me to carry on the memory of my ancestors through tradition—with my Bar Mitzvah—as well as with an educational lens—teaching others about the Holocaust and about specific stories of survivors.

Feeling disconnected from Jewish activism, I decided to become an educator on the Student Leadership Board of the Seattle-based Holocaust Center for Humanity last year. Each week, we met to discuss present-day instances of oppression and discrimination across the world, and finished the year by building a website to share the story of a Holocaust survivor. 

Being on the board connected me to a network of other passionate Jewish activists, and helped me to channel the pride for my culture and ancestors into visual media that reaches many viewers. At Colgate, I hope to find myself surrounded not only by like-minded Jewish students, but by a diverse group of people with whom I can learn and make connections. (196 words)

Tips + Analysis

1. Highlight a core identity. In the example essay, the applicant highlights their Jewish heritage and the profound impact it has had on their life choices and commitments. This is a great way to approach this prompt—think of communities/identities that you claim, pick one that Harvard isn’t seeing elsewhere, and show how that aspect of you + your experiences will allow you to contribute to the Harvard community. Similarly, for the Harvard prompt, ensure you shed light on the aspects of your background that have shaped your identity. This could be cultural, familial, or personal attributes that have molded you into the individual you are today.
2. Provide concrete examples of impact. Just as the sample essay vividly narrates the applicant’s journey in Jewish activism, so you’ll want to offer specific instances that exemplify the impact your background has had on your decisions and pursuits. Whether through personal experiences, engagements, or projects, share specific moments where your background has led you to initiate meaningful actions. In short, show us.
3. Connect to Harvard’s community.  The sample essay could be stronger if the writer reflected even more on how they might continue to nurture their identity at Harvard. How can you do that? Address how your background, values, and commitments align with Harvard’s vision and how you intend to extend these connections on campus to foster learning and shared growth. For example, perhaps you plan on joining (or creating?) relevant student clubs, volunteering at a local museum, or finding innovative ways to connect with students who share a similar background.

Another example essay:

You wouldn’t think an American Asian Affinity Space would be diverse, after all its whole premise is centered around one specific identity. However, members of the affinity space at my high school come from several different grades, genders and ethnicities. The group included a sophomore from China, a junior from Pakistan, and members from Korea, Japan, and even Israel. We each had unique stories of living as an Asian-American, yet, we had all chosen to come to this affinity group. As we spent time together, we were able to find shared experiences, like our parents preparing packed lunches for us from our country and being too embarrassed to bring them to school. Whether eating humbow or biryani, we all knew what it was like to feel out of place. 

My work with the AAAS got me thinking about what diversity can look like, and what it means to embrace diversity. On the one hand, you can find diversity even when people appear to be alike. By exploring our differences, we can continue learning from each other even when it seems we have shared backgrounds and values. At the same time, people who seem really different may have shared human experiences, feeling like the “other” or being embarrassed by their parents, that can bring them together. Moving forward, I want to learn about people’s differences, hearing their stories and learning about their backgrounds while also creating spaces for people to have shared experiences that bring people together.

This is truly optional, so don’t feel obligated to write something here. And you may already be covering this in your additional info section.

This section exists so that your readers understand the full context of your application—so if you were impacted in ways they mention, help them to understand.

Generally, you can keep this informational in tone. You can probably even go with bullet points if you want.

 

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Want advice on dozens of other supplemental essays?
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Special thanks to Elica for contributing to this post.

Elica (she/her) is a college essay specialist who has a love of language in all forms; she has degrees in linguistics, has taught academic writing at the university level, and has been coaching students on their college and graduate school admissions essays for over 7 years. When she’s not working with students or writing, Elica can be found reading, printmaking, and exploring nature. 

Top Values: Collaboration | Curiosity | Patience