Some of the attitudes and actions of teenagers are to be expected, just because they’re teenagers. They’re going to be sullen sometimes, sometimes they’ll be happy, and sometimes they’ll just be downright obnoxious. However, if teen behavior goes beyond this, for instance if they are violent, destructive, or physically or verbally abusive parents are going to want to take some initiative to try to solve these problems. They could be signs that the teen is being bullied at school, or that they are just having problems with their peers. It could also be that they have issues that they don’t know how to deal with, such as peer pressure. There are any number of problems that they could be having. As a parent, you need to be aware of the symptoms so that you can address the problems. If they’re having problem solving issues, perhaps a program like the Total Transformation by James Lehman is worth looking into.