For a girl, I think it can definately send the wrong signal.. it can tell the guy that you're easy, and let him think you're not looking for a REAL relationship that will last.. it can also make him not respect you.. For a guy, It can tell the girl that you are just here for one thing, and make her feel played and foolish. It can cause her to not trust you. And both can make you seem desperate.. I think its best to try to wait til marriage, but understanding the world we live in and that Im definately not one to judge (we didn't wait til we were married, i think one should definately not have sex on the first date.. to avoid quickly complicating or even ending something that may have turned out great! I have never regretted making love to my husband, but looking back now there are things we went thru that could have been avoided had we waited til we were married.