If you know you'll need someone your child might not know to pick him up, choose a code word that the person can give the child to let him know he's trustworthy. Keep current pictures of your child printed out and accessible - -they won't do a lot of good if they're sitting on your digital camera and there's nothing to show authorities if your child goes missing. Consider keeping pictures in a booklet that contains your child's fingerprints (easily made with a stamp pad) and any defining characteristics, such as a mole, birthmark or other physical distinction. It's tough to keep kids occupied during the summer, but don't drop them off at parks, malls, arcades or other public areas unsupervised. If you must leave older kids home alone, set some ground rules, including what to tell strangers who call or come to the door - or not answering at all. Finally, listen to your kids and ask about what they're doing this summer. Keeping the lines of communication open is the best way to tell if your child might be in danger.