This is one of the most annoying things to have popping up in your mind all the time. You want to find out, but don't know how to go about doing it. Sometimes the direct approach is best--just ask. But if that seems too bold for your liking, look for the following signs.
Pay attention to your conversations with the person in question. Does this person show a special interest in having a conversation with you and, once started, make an effort to keep that conversation going?
Is this person "accidentally" running into you in places where he or she knows you will be, such as at your desk? At the Laundromat on Tuesdays? At your brother's birthday party?
Make a note if he or she mentions future plans to spend time with you: "That band is coming to town soon. We should really get tickets."
Spend time alone together. Canceling other plans in order to be with you longer, or not finding excuses to leave, could be a sign of interest.
Has he or she been calling for random reasons, such as, "I was wondering if you knew what that pizza place down the street is called," followed by, "Are you hungry?"
Has this person taken a sudden interest in your life and hobbies? This is a sure sign that he or she is interested in something - and it's probably not your stamp collection.
Observe how the person acts around your friends - he or she might be extra friendly to your closest pals for a reason.
Sometimes seeing someone you have a crush on results in telltale physiological signs. Does the person in question blush when you look at him or her? His or her sympathetic nervous system is probably going into overdrive. Does he or she have trouble speaking, using jumbled words when talking to you?
See if the person in question mirrors your motions: When you lean back, he or she leans back; when you put your elbows on the table, he or she does the same.
Note whether this person sits or stands in the open position - that is, facing you with arms uncrossed. In addition, a woman tends to cross her legs in a man's direction.
Does he or she move closer to you and/or touch you subtly, such as with a pat of your hand or a touch of your cheek?
Other elements of body language include frequent eye contact, holding your gaze and looking down before looking away, energetic speech coupled with open hands, and flashing palms.
Does the person you're wondering about just plain smile at you a lot?