You've probably already figured out that your teen is looking to find more independence from you, to stretch his/her wings a bit. Getting some separation from parents is a normal, even healthy part of adolescence. However, this doesn't mean you should just step back and let your teen do as he/she pleases. Such permissive parenting can often lead to behavioral problems, so you do want to maintain control over your teen's behavior.
The best way to maintain that control while also letting your teen test the waters of freedom is by staying in touch with your teen and what he/she is doing. At a minimum, you'll want to know at any given time where your teen is, who he/she is with, what he/she is doing, and when he/she should be home. In order to keep the lines of communication open with your teen, so you have this information directly from him or her, it's a good idea to take consistent action that lets your teen know that you are interested in and an active part of his or her life.
One thing you can do to keep in touch with your teen is to find a true, common interest you share. You can then find ways, based on such interests, for you and your teen to spend time together. Equally important is letting your teen engage in activities, whether at school, a religious institution or elsewhere, without you. The way to stay in touch here is to ask your teen about these activities. Listening to what your teens have to say about how they are spending their time accomplishes two goals. First, you're showing your teens that you care about them and their unique personality, which will make your teens feel good. Second, you're getting that valuable information about where your teen goes and spends his/her time (and with whom) that really lets you know about your teen's life.