<p>YGD,</p>
<p>Not sure, maybe to keep up with the Jones since H&P also allow rolling schools:</p>
<p>[Harvard</a> College Admissions § Applying: Early Action](<a href=“http://www.admissions.college.harvard.edu/apply/application_process/early.html]Harvard”>http://www.admissions.college.harvard.edu/apply/application_process/early.html)</p>
<p>[Princeton</a> University | Single-Choice Early Action](<a href=“http://www.princeton.edu/admission/applyingforadmission/single-choice-early-actio/]Princeton”>http://www.princeton.edu/admission/applyingforadmission/single-choice-early-actio/)</p>
<p>Being the only SCEA school to restrict OOS rolling publics might have put Y at a disadvantage in the arms race. Also, they used to allow all rolling (D1 applied to an OOS rolling public in 2007) but changed it to only your IS public a few years ago IIRC.</p>