I've been through some of this with my son.  To tell you the truth, you may have to take away some of his independence, especially when it comes to tv and internet access.  You can change his access on the internet yourself easily and you can always remove the tv from his room if that's where it is.  Drastic?  Not really - how many of us actually grew up with a tv in their room?  I didn't and I'm sure thousands others didn't and we're probably better for it!  If you want to change his friends, that is a little more difficult.  I was going to a church that has a great youth group and told my son that I wanted him to try it out.  He actually really likes it and it is helping.  If you do not want to go that route, I'd say the best option is to move him to another school, which would mean uprooting the entire family and home in most areas.  If you don't move you can always try and get him into another school in the same district next year, but you would have to provide his transportation to and from the school.