<p>The Harvard admissions committee is a bunch of people who love to be right. If they have to rescind admissions, it means they were wrong. Which they hate. So they are extremely reluctant to do so. B+s are not going to hurt you at all. To get rescinded (approximately one admission is rescinded each year) you need to be failing or commit a violent crime.</p>
<p>I know of a kid who got his Yale EA admission rescinded for getting two Cs. I don't know where the borderline is. Is it three Bs? one C? two Cs? Who knows? But the larger question is, having achieved something that the vast majority of kids can only dream of, why risk it all by letting your grades slip? Just keep doing what you've been doing to get this far.</p>