For many parents, the hardest thing that they can see their child go through is high school. High school is a time where many children learn to become adults and learn about who they are. However, the people that your child may be looking towards for an example may be their friends rather than you. If that is the case, and your child is falling into peer pressure, then you need to make sure that you are there for them rather scolding them.
Peer pressure is a something that you can not control, no matter how badly you want to protect your child. The best thing that you can do for your child is to talk to them about what they are going through. This is not the time for you to yell or to get angry. While peer pressure can certainly lead to scary and harmful things, the peer pressure that your children may be facing may not be nearly as serious. Even if the situation is serious, you need to remember that they are learning. When children make mistakes they are often making them because they do not understand the consequences of their actions. Many teenagers are still dealing with a sense of invincibility. So rather than yelling, listen to why your children felt they had no other option but to participate in the behavior.
If your child is participating in harmful behavior you need to work with them to determine what is the best option for helping them not make bad choices again. If it is simply that they made a mistake and they will not do it again, then you should drop the issue. However, if the issue is serious enough then you may have to consider relocating your child to another school or making sure that they meet a new group of friends. In many cases, if you work with your child to come up with a solution they will more likely to stick with the plan and not give into temptation rather than if you just put a mandatory sentence on them.