Which is more selective: Notre Dame or Duke for undergraduate admissions?

The biggest practical tradeoff in comparing Notre Dame and Duke is that both are true reach schools, but Duke is usually viewed as the slightly tougher admit overall. In most admissions conversations, Duke is treated as a notch more selective because of its larger national and international applicant pull and the intensity of demand across its programs. Notre Dame is also extremely competitive, just not usually placed quite as high on the selectivity ladder as Duke.

That said, the gap is not so large that it changes your strategy much. For an applicant building a college list, both belong in the reach category unless your profile is exceptionally strong and especially well aligned with one school.

Another reason this comparison gets messy is that selectivity is not identical across every applicant type. Duke often feels especially difficult because it draws a very broad applicant pool from students aiming at the most selective private universities in the country. Notre Dame can be somewhat more predictable in mission and institutional culture, which can matter for fit, but that does not make it easy.

So if the question is simply which school is more selective for undergraduate admissions, the usual answer is Duke by a modest margin. I would still treat both Notre Dame and Duke as serious reaches rather than assuming one is meaningfully safer than the other.