<p>if we assume that colleges do things purely out of self-interest, then obviously Princeton initially signed on with CommonApp so that it wouldn’t miss out on the huge pool of CA applicants who wouldn’t have applied otherwise if not for the supreme ease of sending their apps in to “try their luck”. A larger applicant pool keeps the acceptance rate low - something they could boast about. </p>
<p>but they’re obviously not gonna deny a qualified and compatible candidate when they come across one, whether CA or PA.</p>
<p>for those of the opinion that using PA is a way of “expressing interest”: expressed interest doesn’t matter much to schools like Princeton.</p>