A: As a "tween," your 11 year old is entering a tough developmental stage which could get even tougher as she enters her teen years. But moodiness may be associated with more than early adolescence. Depression is under-appreciated in kids, and mood changes can be tied to a variety of problems at home, at school (social struggles, academic issues, bullying, abuse), or with drug/alcohol experimentation. Talk to your daughter one-on-one and try to understand the basis for her unhappiness. Look for simple things you can do to help her. Review her school performance, discuss her friends, and make sure you're aware of her after-school activities. Simply spending more time together, without her sibling, may be enough. If she doesn't open up to you and the problems persist, consider seeing a family therapist together.