I tell every family I work with the same thing in our first conversation: before you trust anything a college's website says about itself, find that school's Common Data Set. It is the single most useful document in the entire admissions process, and almost no one outside of counselors knows it exists.
What the Common Data Set actually is
The CDS is a standardized survey that around 1,000 US colleges fill out every year, using the exact same questions and section numbers across every school. It was created by a joint effort of College Board, Peterson's, and U.S. News so that data publishers could compare schools on identical terms. Because the format never changes, once you learn to read one school's CDS, you can read any school's CDS.
How to actually find it
Search '[school name] common data set 2025-2026' (use the most recent academic year you can find). Skip the admissions.edu marketing pages entirely and look for a PDF, usually hosted on a page called Institutional Research, Institutional Effectiveness, or the Registrar's Office. Some schools bury it two or three clicks deep; a few don't publish it publicly at all and you'd need to request it, though that's rare among schools that compete for rankings.
Section C7 is the section that matters most
Section C7, 'Relative Importance of Academic and Nonacademic Factors,' lists roughly 20 factors, rigor of curriculum, GPA, class rank, test scores, essays, recommendations, extracurriculars, character, demonstrated interest, legacy, and more, and rates each one Very Important, Important, Considered, or Not Considered. This is the school telling you, in writing, filed with the federal government's IPEDS system, what it actually weighs. I've had students discover that a school they assumed cared deeply about extracurricular leadership actually rated it only 'Considered,' while rating rigor of curriculum 'Very Important,' and that changed how they spent their final semester of course selection.
Section C21 tells you the real test score range
Section C21 gives the 25th and 75th percentile SAT and ACT scores of the students who actually enrolled, not the applicant pool, the enrolled class. If your score sits below the 25th percentile, you're a reach on testing alone regardless of anything else in your file. If it sits above the 75th percentile, testing is not going to be what holds your application back.
A student example
A student I worked with was building her list almost entirely off a magazine ranking and her guidance counselor's general sense of each school's reputation. When we pulled the CDS for her top six schools, we found that two of them rated demonstrated interest 'Very Important' and two rated it 'Not Considered.' She had been treating all six the same way, sending the same number of emails and doing the same virtual info sessions everywhere. Once she saw the data, she redirected her limited time toward the two schools where it would actually move the needle, and skipped the theater at the two where it was wasted effort.
Mistakes families make with the CDS
- Reading only the admissions website's stated 'holistic review' language instead of the CDS numbers behind it
- Comparing a school's CDS from three years ago instead of the most recent one, missing policy shifts like reinstated testing requirements
- Never checking C7 at all and assuming every selective school weighs the same factors the same way
- Ignoring Section H and only looking at the sticker price, then being surprised by the actual aid offer
What to do with this
- Pull the CDS for every school on your list, not just your top choice
- Read Section C7 first and compare it across your list
- Check Section C21 against your actual or projected test scores
- Use Section H to sanity-check a school's financial aid reputation before you fall in love with it
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