Get Educated: First, learn as much as you can about substance abuse in general, including alcohol and tobacco.  Attend available educational events.

Act Now: Begin to more closely monitor your teen's activities. Keep track of changes in behavior, appearance and friends.  Find out who is on your teen's Internet buddy list and what sites are bookmarked as favorites.

Don't Make Excuses: It's natural for parents to be tempted to make excuses for their child or teen's behavior - but this type of enabling actually makes it harder for a young person to become responsible and self reliant.

Have the Talk: (Or - Let Them Know You Know) It's not easy to confront someone with your concerns, even when it is your own child.  It is much harder to simply watch and worry when you believe your teen is following a self destructive path.    Have the talk when you are calm and have plenty of time. Pick a time when your teen is not impaired or high - even if it means waiting a day if your teen comes home drunk or reeking of marijuana. For more specific tips on discussing your concerns with your teen, check out See It Say It.

Remember that you are not the first parent to deal with these issues, and you don't have to do it alone.  Discuss the situation with someone you trust.  Take the time to take care of yourself while you are in the midst of this situation.