If you like your essay as it is, use it for the schools with really short limits.Now, as for the other schools. Unless you think your essay ROCKS at 500 words, I'm sure you have more to add. The word limit is less important for most schools than the two page rule of thumb. In other words, they say 1000 words because it is a nice round number, but your PS will look longer than everyone else's if it is over two pages, and will look shorter if it is 500 words.For those schools I would suggest adding another paragraph, perhaps you can tell a nice story that sets a memorable scene or something. Two pages is about 750 words BTW. MOST IMPORTANT: quality matters more than anything else, if you think adding another word will make you essay LESS good, than by all means keep it the length that it is. For me though, I am struggling with just the two page limit, I feel like there is too much about me to be contained in a space that small. I'm sure that's true for you too.Just my two cents, based on everything that I've read. Good Luck!