Lori
First, you need to let her know that this is natural and help her maintain her self-esteem. Second, many local hospitals and clinics have "growing up" classes that explain to young girls what will start to happen to their bodies as they mature. Call ahead and make sure they have a class appropriate to your daughter's age. Let her invite a friend to go along with her. Many Girl Scout troops in my area attend these types of classes together as a group. Also, help her pick out some clothes that she'll feel comfortable in. You may see that she'll start wearing baggier clothes, sweatshirts, etc, to try to hide her developing bustline. One of her biggest fears will probably be changing her clothes in front of other people - gym class, etc - so help her pick out some pretty, supportive bras (try sports bras). If you think she's beautiful, she'll feel that way also hopefully. I'm also assuming that you've talked to your pediatrician about this and also her brothers (if there are any) about not teasing her.