As a rule, I don't like to leave my kids alone at home. Sometimes, however, it can't be helped and the most important thing for the kids is having the knowledge and confidence of what to do in the event of a problem. The best way is always being prepared and knowledgeable and the book "A Smart Girl's Guide to Staying Home Alone" is a great way of giving your daughter the wherewithal to feel in control. This book also makes a good read for parents as a basis for talking to your daughter about certain topics, dangers, safety etc.
The book covers topics such as: safety (knowing your neighborbood, be in control of your key etc); how to tackle sibling conflicts when parents are out of the house; boredom busters, i.e. ideas of how to entertain yourself; first aid and how to stay in control in tricky situations and it even includes recipes, when hunger hits your kids after school.
Another great feature is, in my opinion, the special pull-out for parents and kids to write down all important information (i.e. phone numbers) as well as house rules.
Overall, this book would give, in my opinion, kids and parents peace of mind knowing that everybody is aware of the house rules. It also prepares kids to feel confident and in control when they are alone at home.