My 12-year-old daughter has been having angry outbursts. About once a week, she will get angry, and yell and stomp out of the house or run away. She has also been lying. What can we do to help her? We think she could be bipolar.
I am not sure why you think your daughter may be bipolar, but in my opinion as a professional counselor, I do not in your narrative see any symptoms of a bipolar condition. Quite frankly, I see a young child who is out of control. I strongly encourage you to seek out a good parenting skills group, or family counseling, or to go to your local library and pick up some of the very good books available on dealing with out-of-control or hard-to-handle children.
Running away one or two times a week is quite dangerous to your daughter's physical and emotional well-being. Where does she go? With whom does she stay? Do you file a runaway report with the police? How long is she gone? What are the consequences when she returns? If you can afford it, get a complete psychological evaluation to rule out any serious emotional problems, but most of all help yourselves and her by learning all you can about good parenting.