Generally, one personal statement should work for you to send to all of the schools you’re applying to. You want it to be the best representation of you as a person, so there’s no reason it would need to vary greatly from one school to the next.
That said, sometimes a particular school may have a program that dovetails nicely with your intended focus of study and/or essay theme, so do feel free to tweak your PS to better suit individual schools.
Don’t go overboard with it though; always make sure your essay focuses mainly on you and what you can offer the school and not the other way around. Adcomms already know their schools are awesome, so there’s no need for you to go into detail about why.
The huge caveat here, of course, is to make absolutely certain you send the correct statement to the intended school. I know this is trite advice, but here goes nothing: don’t send your Yale statement to Harvard. This happens every year to someone in the applicant pool, so just don’t let it be you.
Ready, set, WRITE!
*Image by Keith Williamson (Flickr) via CC license.