While it's a teenager's job to push the limits and drive you to distraction, running away goes beyond that and usually indicates some deep-seated problems.
They're usually running from a situation they believe can't be solved by staying at home - life will be better for them elsewhere.
It could be a fear of what's going to happen when they get found out about something, a fear of going to school for some reason such as bullying or humiliation, physical or sexual abuse, or something that's happening at home, or it could be a manipulative strategy or being sick of "being told what to do''.
The physical or sexual abuse situations are understandable and generally it takes action by the police or social agencies to get these sorts of cases resolved.
The other kinds of situations are much more complex. These teens feel that their school is unsafe, or that their parents are unreasonable, immovable and don't care about their feelings or needs. They often feel neglected and unloved even though they appear to live in a loving and caring environment.
The intervention of a relative, family friend or school counsellor is often needed to get both parties talking and to get to the bottom of the problem.
When a teenager announces they're going and "you can't stop me''. They're right. You could try to calm them and suggest that they sit down for five minutes to think this through and leave them in peace to do this.
Depending on the situation, you could then ask questions such as: "What's going on?'' "What's so bad that it's made you want to leave?''
"What's so bad that you can't see a way through or can't handle it?'' Then maybe: "OK, you made a mistake let's see if we can work through this together, get it sorted and get on with life.''
If they leave, they'll usually head to a friend's place. You mightn't approve of the friend or the parents, but at least you know where they are and hopefully they're relatively safe.
If you feel they are safe enough, leave things for a day or two to let emotions settle and then work through an intermediary to get to see your teen on neutral territory.
From there, it's a case of playing it by ear and professional support can be very useful. You may have to listen to and try to understand accusations that are patently false or unreasonable and some that you'll need to think about very seriously. Don't expect or try to resolve matters in one meeting - these things take time.