California Institute of Technology (Caltech) 2025-26 Supplemental Essay Prompt Guide

California Institute of Technology (Caltech) 2025-26 Application Essay Question Explanations

The Requirements: 7 short essays ranging from 100 to 250 words each

Supplemental Essay Type(s): Community, Activity, Oddball, Why, Short Answer

How to Write Caltech Supplemental Essays

Caltech’s supplement is chock full of short answer questions. As you wade through questions about your academic interests, projects, and passions, remember that Caltech seeks students who aren’t afraid to dive into the deep end of the pool: “Failure […] isn’t anything to fear. Our question is: How will you handle that?” Spend some time brainstorming about all your interests and experiences, whether successful or not, and you’ll get through this supplement swimmingly. Read on for more detailed advice on your Caltech supplemental essays!

Your STEM Future: Academic Interests

Caltech has a rigorous core curriculum and students don’t declare a major until the end of their first year. However, some students arrive knowing which academic fields and areas already most excite them, or which novel fields and areas they most want to explore.

If you had to choose an area of interest or two today, what would you choose? Note that you are under no obligation to follow this choice if admitted.

There’s only one trick to selecting a major or generating a straightforward list of your academic interests: be honest. If you already know what you want to major in or have it narrowed down to two choices, you’re set! Don’t waste time trying to strategize because choosing anything other than your true interests would be a misrepresentation of who you are and a disservice to yourself and the admissions office. This assignment will, no doubt, be most challenging for the undecided, but ask yourself: how can I use this opportunity to reveal something about what excites me intellectually or academically? 

Why did you choose your proposed area of interest? If you selected ‘other’, what topics are you interested in pursuing? (Min: 100 / Max: 200 words)

You’ve only got 200 words, but if you chose wisely in the previous question, answering this one should be easy as pie. Whether you listed one or two interests, your goal here is to tell a cohesive story about your intellectual curiosity. Ideally, you should try to recount an anecdote that illustrates your engagement with your chosen field or demonstrates your ability to link together seemingly disparate fields. Perhaps you’re interested in both philosophy and astrophysics because each offers a way for you to contemplate our place in the universe. This is a great opportunity for you to explain how your intellectual interests relate to who you are as a person. Don’t waste it!

Required Short Answer Questions

Your STEM Present: Curiosity

Regardless of your STEM interest listed above, take this opportunity to nerd out and talk to us about whatever STEM rabbit hole you have found yourself falling into. Be as specific or broad as you would like. (Min: 50 / Max: 150 words)

Admissions wants to learn more about a STEM topic that has monopolized your thoughts. When was the last time you went down an internet rabbit hole trying to research something? When were you extremely motivated to solve a problem or create something new? What topic are you hoping to be an expert on by the time you graduate college? Discuss an example of what truly fascinates you. Perhaps you’re really interested in the future of smart prosthetics. Maybe you’re obsessed with identifying Fibonacci sequences in the world around you. Share how you’ve already interacted with your area of interest: Did you attend a seminar about the topic? Have you read every book you can find on it? Do you have a personal connection to it? The bottom line here is to write about something that really fascinates you and share your enthusiasm for STEM. 

Your STEM Past: Prior Experiences

At Caltech, we investigate some of the most challenging, fundamental problems in science, technology, engineering, and mathematics. We are interested in learning more about your engagement with STEM.

Select one of the following two STEM experience prompts to respond to:

Tell us how you initially found your interest and passion for science or any STEM topic, and how you have pursued or developed this interest or passion over time. (Min: 100 / Max: 200 words)

Tell us about a meaningful STEM-related experience from the last few years and share how and why it inspired your curiosity. (Min: 100 / Max: 200 words)

For these two short answer responses, we recommend using concrete sensory details to pull your reader into the story. For the first one, try to remember the moment your passion for science was sparked and caught fire. Was it a trip to the local observatory? Was it when you were mesmerized by a grandfather clock at your uncle’s house? Trace this initial moment to today, explaining how you have developed your interest over time. How did this experience lay the foundation for your future STEM-related pursuits? Strong responses will make the readers feel like they’re in the room where it happened (“the room where it happened” – Hamilton). As you write your response, make sure you include every detail you can remember; once it’s all on the page, you can edit it down to meet the 200-word limit. 

Now, for question two, think about a project you’ve done more recently that captured your attention and curiosity. What excited you about it? How did you develop your skills or interest in STEM as a result of your participation? If you’re applying to Caltech, we’re willing to bet you have a few experiences to choose from, so we recommend writing about the one that was most meaningful for you. Did you work on a clinical trial for a treatment of the autoimmune disease that your sister has? Were you part of a group engineering new wells for an impoverished community in Appalachia that’s quite close to your own home in West Virginia? Think about your values and passions and how your experience relates to or fuels them, and you’ll ace this response. 

Creativity in Action

The creativity, inventiveness, and innovation of Caltech’s students, faculty, and researchers have won Nobel Prizes and put rovers on Mars. But Teachers also imagine smaller-scale innovations every day, from new ways to design solar cells to how to 3D-print dorm decor to experimenting in the kitchen. How have you been a creator, inventor, or innovator in your own life? (Min: 200 / Max: 200 words)

Admissions is seeking to invite movers and shakers to campus who are excited and motivated to turn their dreams into reality. Whether you’ve been experimenting with robotics or spending your summers researching ways to integrate renewable energy into daily life, this is the place to share your story. Show admissions that you are not only planning to be an innovator, but have already taken steps to incorporate this approach in your day-to-day activities. The more specific details you can incorporate into your essay, the more sincere and personal it will feel (and be!). 

Now it’s time for a little fun!

You have 250 words total to answer two of the four questions below.

It’s up to you how you use your 250 words, whether that means you use exactly 125 words for each answer or you tell us about a niche interest in 30 words so you can spend 200 telling us about a core piece of your identity.

There is no ‘right’ way to choose which question to answer. If you’re all STEMmed out, feel free to tell us about a creative hobby. Or if you just can’t get enough math, tell us about a concept you can barely wrap your head around. 

Just remember the Caltech Honor Code and stick to 250 words total. Select a prompt from the list:

Hobby: What is an interest or hobby you do for fun, and why does it bring you joy?

What do you do when you’re not busy with school, work, and other responsibilities? Do you love ‘90s sci-fi shows and their visions of what future technology could look like? Do you invent and play card games with your siblings? Do you meticulously research and select native plants to put in your garden? Don’t worry about choosing something STEM-related or that you think sounds good to admissions; stick with whatever truly brings you joy, and your unique qualities will shine through.  

Teach: If you could teach a class on any topic or concept, what would it be and why?

This is another opportunity to share something about yourself that hasn’t yet appeared in the rest of your application. Reach beyond the traditional academic areas and toward skills you may have cultivated on your own time (e.g., gardening, rock climbing, baking, etc.). What are you good at? What topic could you wax poetic about for hours on end? Your topic here could be STEM-related but doesn’t have to be. Would you teach a class on the politics of the modern heroine in YA fiction? Perhaps you’d discuss deep-sea marine life in the Pacific Ocean. There is no right or wrong answer here, so write about the subject that interests you the most!

Identity: What is a core piece of your identity or being that shapes how your view and/or interact with the world?

Caltech knows that you are a multifaceted person, that your identity cannot be boiled down to nuggets of information on an application. That’s why admissions is giving you this (albeit small) space to expand on an aspect of your identity. Scroll through your application (personal statement, activity list, major selection) and take a moment to think about what you haven’t been able to include yet. Perhaps you want to write about your identity as a first-born daughter of immigrants or the daily yoga practice that grounds you and enables you to better connect with people and places around you. Make sure you write about something that has affected your worldview or that influences how you interact with others. Regardless of what you choose to write about, you don’t have a lot of words to play with, so we recommend brevity!

Concept: What is a concept that blew your mind or baffled you when you first encountered it?

CalTech wants to accept intellectually curious applicants, so take this opportunity to rant and rave about one of your obsessions! What was the last person, place, idea, theory, or skill you learned about that truly captured your imagination? Perhaps learning about special relativity in physics class revolutionized your view of the world around you. Maybe your mind was blown by the marvels of ancient architecture, and you can’t stop theorizing about how the Greeks built the Colossus of Rhodes. The bottom line here is to discuss examples of what truly amazed you when you first discovered it while also sharing about your personality traits, interests, or passions.