It sounds like you're in a difficult spot. Whether or not you decide to tell your best friend about your feelings, your relationship is probably going to go through some changes.

I guess one way to decide about speaking up is to think about whether the feelings--or your friendship--are likely to go away. If this is a short-lived crush or a friendship that will definitely end with the start of college, that may be an argument for not saying anything.

On the other hand, strong feelings can't usually be just shoved under the rug. And moving apart to go to college doesn't necessarily make best friendships fizzle.

Another idea is to think about all the ways your friend might react if you tell her. If she doesn't feel the same in return, you could feel pretty bad. Are you prepared for that? What if she does feel the same? Has she given you any hints that she does?

If you can be honest with yourself about what you want and what you truly hope to get back from her--but also try and roll with the punches--your question will probably answer itself.

Meanwhile, you might take a look at these resources about sexual preference and this advice about falling in love with your best friend.