<p>MS, a college who has an ED applicant decline to attend may contact the high school guidance office to get the GC’s story on what the problem is. The GC can’t be expected to lie for a student, as doing so could jeapordize his/her credibility and perhaps even future admits from that HS. In some cases, GCs sign the ED commitment.</p>
<p>There are no absolute answers here. Will School X absolutely know if you broke an ED commitment with School Y? Unless the colleges are close peers, perhaps not. You can’t guarantee they won’t find out, though. In addition to GC issues, a classmate who got rejected might notify the college just for spite.</p>
<p>Best approach: if you aren’t absolutely sold on one school as your first choice, don’t do ED. The marginal improvement in odds isn’t worth the risk of having to decline a school you would prefer to attend.</p>