Discussion. Pot is NOT heroin or cocaine or meth or any of the other things you should be worried about. It's no more a gateway drug that alcohol or tobacco - both drugs (by definition), both legal and both can be lethal. So, I'd have the conversation about it with him, tell him you never expect to find paraphernalia in the house again and that you hope he makes the right choices. Let him know where you stand - if he gets busted, you won't bail him out, remind him it is still illegal. Most kids are not "pot-heads," they're experimenting, just like they do with the alcohol you buy at the local store, and with sex. Make sure you figure out where he is on that scale. Treat him like an adult - don't scream and rant. This is a great opportunity to see where he will go as far as making good choices as an adult. (college isn't too far away). Don't panic. Not defending it - but there a thousands of grown adults who occassionally indulge and do just fine in their lives (again, it is presently illegal, so I am not condoning it). Have an adult conversation and give him an opportunity to speak, be heard and to then act like an adult himself. Don't go hard-core until there is evidence you actually need to.