How to Get Into Castilleja School: A Complete Admissions Guide for Parents

A test-free, interview-heavy process at Palo Alto’s only nonsectarian all-girls school. Here is what the committee actually weighs.

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Everything Bay Area families need to know about applying to Menlo School in Atherton, from the required STAR Assessment to the March decision date.

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Quick Answer for Busy Parents

Getting into Castilleja requires a strong transcript, three division-specific letters of recommendation, a timed online writing sample, an interview, and questionnaires from both the student and the parent. No admissions test is required. Castilleja does not consider the ISEE, SSAT, or STAR results and will not add them to a file if they are sent. Applications open September 1, 2026, and close January 5, 2027, with decisions posted March 12, 2027. Sixth grade is the largest entry point, with roughly 60 seats and several hundred applicants.

Why Do Families Choose Castilleja School?

Castilleja was founded in 1907 by Mary Ishbel Lockey, a Montana native who graduated from Stanford in 1902 with a degree in English and was encouraged by Stanford’s first president to start a school. Nearly 120 years later, it is still the only nonsectarian all-girls middle and high school in the San Francisco Bay Area, on the same block of Bryant Street in downtown Palo Alto.

The motto is Women Learning. Women Leading, and the school builds its program around research on how adolescent girls learn, favoring deep-dive interdisciplinary work over coverage. Families choose it for that combination of seriousness and warmth. In Niche’s 2026 rankings, Castilleja is the top-ranked all-girls high school in California and eighth nationally, and the highest-ranked private high school in Santa Clara County.

Many families weighing Castilleja are also considering The Nueva School, Crystal Springs Uplands, Harker, and Menlo. What separates Castilleja is not rigor, which all of them have, but the fact that it is single-sex and that it has removed testing from the equation entirely.

Castilleja by the Numbers

The academic program spans nine departments: Computer Science and Engineering, English, History and Social Science, Mathematics, Science, Visual and Performing Arts, World Languages, and Fitness and Wellness. A dedicated three-person office handles college counseling. Castilleja is accredited by the Western Association of Schools and Colleges and belongs to One Schoolhouse, the International Coalition of Girls’ Schools, the National Association of Independent Schools, the National Association for College Admission Counseling, the Western Association for College Admission Counseling, and the Association of College Counselors in Independent Schools. It also partners with and hosts the Peninsula Bridge Program each summer.

Students commute from more than 50 Bay Area zip codes. Castilleja runs free morning and afternoon buses and shuttles, with stops in San Carlos, Los Altos, West Menlo Park, Burlingame, Woodside, Stanford Hills Park, East Palo Alto, and Portola Valley, plus free Caltrain shuttles from the University Avenue station.

How Hard Is It to Get Into Castilleja?

Castilleja does not publish an acceptance rate, and any figure you find on an aggregator site should be treated as an estimate rather than a fact. What the school does say is more useful. The committee reviews several hundred applications for sixth grade and more than one hundred for ninth grade. Sixth grade offers roughly 60 seats. Grades 7 through 11 open occasionally and in far smaller numbers, and twelfth grade is not an entry point at all.

The committee describes what it wants in specific terms: girls who are intellectually curious, actively engaged, and strong members of their current school community, and who embody the school’s five core values. Castilleja calls them the 5 Cs: conscience, courtesy, character, courage, and charity. That vocabulary is worth internalizing because it tells you what the interview and the essays are really assessing.

Because no test score enters the file, the remaining components carry disproportionate weight. There is no strong ISEE result waiting to offset an inconsistent transcript or a flat conversation.

Top Tips for Families Who Want to Get Into Castilleja

• Start the spring or summer before the application year, not in the fall of it.
• Submit the preliminary application early. Interview slots and several events are gated behind it and they fill.
• Choose depth over breadth in activities. The questionnaires reward a student who has gone far in one direction.
• Learn the 5 Cs and find real examples from your daughter’s life for each.
• Target sixth grade if the timing allows. The odds are meaningfully better than at any later entry point.

Best Practices for Applying Families

• Visit campus before submitting so your daughter can reference something specific she saw.
• Practice timed writing. Thirty minutes is the maximum allowed on the online essay.
• Talk to current Castilleja families if you can, and ask what surprised them.
• Keep the parent questionnaire honest, including about growth areas. Committees read past polish.
• Verify every requirement against Castilleja’s own admission pages before submitting.

Common Questions About Castilleja’s Selectivity

Does Castilleja require standardized test scores?

No. Castilleja does not require or consider ISEE, SSAT, or STAR results, and states that submitted scores will not be added to an applicant’s file. The school frames the policy as an equity measure.

What GPA does Castilleja expect?

There is no published minimum. For context on the environment students enter, the median unweighted GPA across six semesters in the Upper School is 3.96, and students below a 2.5 unweighted are placed on academic probation.

Which grades does Castilleja admit?

Sixth grade is the earliest and largest entry point with roughly 60 spaces. The school also welcomes applicants to grades 7, 8, 9, 10, and 11.

The Castilleja Admissions Process, Step by Step

Everything runs through Ravenna, the shared application platform used by many Bay Area independent schools. Create the account first, because it is where forms, event registration, recommendation requests, and status tracking all live.

1. Create a free Ravenna account and submit an inquiry so you receive fall admission communications.
2. Register for Discover Castilleja events, including information sessions and division preview events.
3. Submit the preliminary application, which unlocks interview and meetup registration.
4. Schedule and attend a campus visit and student interview.
5. Sign up for and complete the timed online writing sample.
6. Complete the student questionnaires and essays, plus the Activities and Interest form for High School applicants.
7. Complete the parent questionnaire.
8. Request recommendation letters from the educators required for your daughter’s division.
9. Deliver the signed Transcript Release and Confidentiality Form so her school can send transcripts.

Key Dates and Events for 2026–27

Castilleja publishes firm application milestones but releases individual event times on Ravenna rather than its website. Register as soon as sign-ups open.

Castilleja Application Requirements

Discover Castilleja Events

The fall event series includes admission information sessions, separate Middle School and High School preview events, and parent and guardian meetups. Sessions are largely held on Zoom, and the in-person Preview Days are scheduled for November 9 and November 14. Attendance is not scored, but families who attend arrive at the interview with something concrete to talk about, which shows.

Preliminary Application

A short form collecting essential information about your daughter. It must be submitted before she can register for a campus visit or interview, and before parents can register for a meetup. Fee waivers are available from the admission office on request.

Campus Visit and Student Interview

The interview is required. Middle School applicants have a conversation of roughly 15 minutes following their campus visit. High School applicants interview for about 20 minutes on Zoom, with sign-up information emailed after January 5, 2027. Castilleja is emphatic that there are no right answers and that conversations should unfold naturally. In practice, the students who do best are not the most polished. They are the ones who can say something true and specific when asked what interests them.

Online Writing Sample

Required of every Middle and High School applicant. Students type a response on a computer in a virtual, timed exercise. The task is designed to take 15 to 20 minutes, with 30 minutes as the maximum. Registration runs through Ravenna. Most students can produce ideas quickly. Fewer can organize them into something coherent before the clock runs out, and that is what the sample measures.

Student Questionnaires and Essays

Applicants complete questionnaires and essays describing what matters to them. High School candidates also submit a Student Activities and Interest form, which is where outside pursuits belong. This is the part of the application your daughter controls most completely, and the part where a distinctive candidate separates from a merely accomplished one.

Parent Questionnaire

Parents and guardians complete a separate form. Castilleja describes it as a way to understand what motivates a daughter to apply. The committee is evaluating how well you know her, so a description that includes where she struggles reads as more credible than one that does not.

Recommendation Letters

The requirements differ by division, and families applying to Middle School frequently miss that a second, prior-year teacher letter is required.

Castilleja publishes separate guidance for homeschooled applicants and for students whose teacher has left the school or taught them two years running. Ask the admission office for those documents if either applies.

Transcripts

Schools send transcripts for 2025–26 and the first grading period of 2026–27, plus any prior standardized testing already on record. Print, sign, and deliver the Transcript Release and Confidentiality Form to your daughter’s current school. Because many schools have not finished fall grading by the January deadline, Castilleja accepts transcripts through the end of January. If your child’s grades are not that great, consider tutoring to ensure an impressive transcript.

Testing

Castilleja does not include ISEE, SSAT, or STAR results in its evaluation. Results sent regardless will not be added to the file. Families who have already begun test preparation are better served redirecting that time toward timed writing practice and interview readiness.

A test-free process is not an easier process.

It concentrates the weight onto writing, conversation, and character, which are harder to improve in a hurry. We help families start early enough that the work is real rather than cosmetic.

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Common Questions About Interviews, Visits, and the Writing Sample

Is the Castilleja interview required?

Yes, for every applicant. It is scheduled through Ravenna after the preliminary application is submitted, and the school advises booking early because slots fill.

Do parents attend the student interview?

No. The student interview is your daughter’s alone. Parents and guardians have their own separate meetings with the admission team through the meetup and information session programs.

How should a student prepare for the online writing sample?

Practice writing a structured response to an unfamiliar prompt in under thirty minutes, on a keyboard. The exercise rewards clear organization far more than vocabulary or length.

Should we submit extra recommendation letters?

No. Castilleja states plainly that it neither requires nor encourages additional letters from coaches, private instructors, or mentors. Outside interests belong in the questionnaire forms.

What Student Life Is Like at Castilleja

Castilleja runs on a six-day rotating schedule, so no class always meets on a Monday morning. Traditions carry a lot of weight here, and much of the social structure is built around them rather than around grade-level cliques.

Did You Know? Castilleja runs a six-day rotating schedule, which means no class always falls on a Monday morning.

Academics

Castilleja does not teach an AP curriculum. Its most rigorous courses are faculty-designed Advanced Topics, or AT, courses, first taught in 2012 and generally reserved for juniors and seniors. They were built around research into how adolescent girls learn and what college faculty expect entering students to know. Students may still sit for a limited slate of AP exams on campus when one aligns with an AT course they are taking. The school recommends students cap themselves at four AT courses per semester, and it does not rank students.

Four centers anchor the program. The Awareness, Compassion and Engagement Center, known as the ACE Center, runs leadership and experiential learning against three competencies: initiative, agility, and purpose. The Bourn Idea Lab was the first FabLab@School established in a United States school, built in collaboration with Stanford, and houses the award-winning FIRST Robotics team, Gatorbotics Team 1700. The Margarita Espinosa Library supports research across the curriculum. The school’s 21st Century Assessment framework evaluates students against those same leadership competencies rather than test performance alone.

Fun Fact: The Bourn Idea Lab was the first FabLab@School anywhere in the United States, established in partnership with Stanford.

The Global Investigator Program sends students to work alongside partner organizations abroad, including the Kampung Halaman Foundation in Indonesia. Global Week engages the whole school in one theme each year; the 2025 theme was Bridging Divides: The Art of Listening, The Journey of Learning. Locally, students partner with LifeMoves, Grassroots Ecology, Special Olympics, the League of Women Voters, and Channing House. Notably, Castilleja does not ask students to count service hours.

Activities and Student Leadership

Affinity groups at Castilleja function as a leadership pipeline. Group leaders can join the Diversity, Equity and Inclusion Leadership Council, where they train in facilitation and raise equity questions with administrators directly. Groups include the Black Student Union, Chinese+, Taiwanese, Korean American Student Association, South Asian, Southeast Asian and Pacific Islander, Latinx, Middle Eastern, Mixed Students, Muslim Student Association, Jewish Student Association, a Disabled and Neurodivergent group, and Questioning, Queer, Here. The annual #ComeAsYouAre event brings students, families, and employees together for student-led workshops and a community potluck.

Athletics

The Gators field 22 teams across 11 sports: basketball, cross country, golf, lacrosse, soccer, softball, swimming, tennis, track and field, volleyball, and water polo. Castilleja competes in the West Bay Athletic League within CIF’s Central Coast Section. Over the past three years, Castilleja athletes have been recruited to NCAA programs at Chicago, Colby, Colorado College, Columbia, Harvard, Harvey Mudd, Howard, MIT, Northwestern, Pomona, Santa Clara, Stanford, Tufts, Virginia, and Yale.

Arts

The arts program spans visual art, theatre, dance, and music, with coursework running from introductory workshops through Advanced Topics offerings in ceramic design, visual arts, music theory and musicianship, and theatre production. Exhibitions, concerts, dance performances, and plays run throughout the year.

Summer Programs

Casti Camp serves students in grades 2 through 9 with a program built around play, creativity, and exploration rather than academic acceleration. Castilleja is also a partner and summer site for the Peninsula Bridge Program, which supports rising fifth graders in reading, mathematics, and computer science, with Castilleja students serving as mentors and the ACE Center involved in programming.

Notable Castilleja Alumnae

Castilleja alumnae have reached the top of science, sport, public service, conservation, business, and the arts. A selection:

1. Penny Pritzker: class of 1977. Businesswoman and philanthropist who served as the 38th United States Secretary of Commerce.
2. Julie Packard: class of 1970. Marine conservationist and Executive Director of the Monterey Bay Aquarium, and a recipient of the Audubon Medal.
3. Amy Chow: Olympic artistic gymnast at the 1996 Atlanta and 2000 Sydney Games and a member of the Magnificent Seven, the first United States team to win Olympic gymnastics gold. She was the first Asian American woman to medal in Olympic gymnastics, and later became a pediatrician.
4. Pamela Silver: Cell and systems biologist at Harvard Medical School and a founding Core Faculty Member of the Wyss Institute for Biologically Inspired Engineering.
5. Grace Slick: Singer and songwriter, best known as a member of Jefferson Airplane and a defining voice of the 1960s San Francisco music scene.
6. Nancy Ditz: class of 1972. Olympic marathon runner who represented the United States at the 1988 Seoul Games.
7. Laura Arrillaga-Andreessen: class of 1988. Philanthropist, author, and Stanford lecturer on strategic philanthropy.
8. Helen Katharine Forbes: class of 1908. Painter and muralist known for landscapes of Mexico, Mono Lake, and the Sierra Nevada.

Cardinal Education helped us navigate the Castilleja process with confidence and clarity. Our daughter is now thriving in 7th grade, and we could not be more grateful.

— Palo Alto parent, Class of 2028

A Final Word

Castilleja tells you what it values in five words, then removes the one metric families are most practiced at optimizing. That is a gift, if you use it. It means the work that makes a strong applicant here is the same work that makes a capable adult, and it cannot be produced in a single autumn.

Give the process enough runway to be real.

We start with an honest assessment of where your daughter is and what a competitive Castilleja application would genuinely require of her, then build backward from the deadline.

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Related Articles

• Notable Castilleja School Alumnae and Where They Are Now
• Inside Castilleja School’s Admissions Process: How Applicants Are Evaluated

Frequently Asked Questions About Castilleja School