When a child matures from childhood to teenage years, the parents’ job changes from management to sales. You can no longer force them to do the right thing, you have to convince them to want to do the right thing.
Not knowing the exact situation, it’s very difficult to give specific advice. But as a general rule, you don’t want to force issues — doing so will only drive the teen further away. You may not be able to convince the teen to dump his friends, but you might be able to influence him not to take on their worst habits. You have to hope that he’s learned enough to resist peer pressure to do things that are very wrong.
Let’s face it — there are things that every teen will do that parents don’t agree with. You have to learn to pick and choose your battles. If you fight your teen over every little issue, not only will your teen resent it, but s/he will not be able to distinguish between the stuff that you are willing to negotiate on and the stuff that is simply over the line. You have to give your teen the ability to explore and find his own identity — even if it means some rebellion. All teens do it and it’s perfectly normal.
Bottom line: don’t lock him in the house and don’t forbid him from seeing his friends — it won’t work and will probably make matters worse. Instead, try working with him to make him know what’s important to you (and by important, I don’t mean every issue — I mean the REALLY important issues). And, above all else, make sure that you keep open lines of communication so that your teen always feels comfortable coming to you — no matter how much trouble s/he may be in.
The Wolf (parent of three current teens)