Whatever you do, please don't give your son too hard a time. He DID come and tell you about it, which is more than most kids would do. If you want him to keep being honest with you and telling you about what is going on in his life, you need to make sure he doesn't feel punished for doing so. You do need to remain hard with regards to your stance on the dangers of his smoking something he couldn't even identify and on drug taking in general. But rather than isolate him, sit down at his computer with him and research the dangers of drug taking. Without condemning him, tell him in a calm way why you are worried about him and what it would mean to you if something bad ever happened to him. Grounding him probably won't stop him hanging around with this boy again, but might make it more exciting to do so. Kids do often quite innocently get dragged into these situations with their friends, especially older ones, and that is a real problem. They love to experiment, are rarely aware of the dangers and are often under peer pressure. I would also get in touch (preferably by phone) with the SLO and ask them to contact this boy's parents. They may well be shocked to find out what their son is up to. You may not have to give the SLO your name, or you can ask that it not be mentioned, so this can be done anonymously to protect your son and your family. I wish you and your family well. :o)