Unless everyone in your household is extremely careful, your indoor cat may dart out and run off. Even cats that are used to going out and know the neighborhood well occasionally disappear. While most will return on their own, some may get trapped in a shed or garage, go too far afield to find their way back, or be mistaken as a stray and taken in by someone.

Proper identification is essential to getting your cat back. He should always wear a conventional collar and identification tag. Choose a sturdy collar made of elastic or with an elastic insert, or one with a "breakaway" feature: a clasp that opens when pulled hard so he won't be strangled if it catches on something like a branch. The collar should be tight enough so it won't slip over kitty's ears unless it's stretched, but loose enough to fit two fingers underneath. If you cat balks at the collar, get him used to wearing it for longer and longer periods of time. Then, never take it off, even when he is safely ensconced indoors.

A range of ID tags are available, from engraved to handwritten. There are also small screw-apart barrels that can hold folded paper. Include only essential information on any tag: your address and one or two reliable telephone numbers with answering machines. The disadvantage of collars for identification is that they can come off. Consider a second, more permanent form: the microchip. Implanted by your vet, the microchip can be scanned by an animal shelter or vet to give the name of the registry where your number is on file. This is not foolproof, though. Some smaller shelters may not have scanners and those that do may not be able to read chips from diverse manufacturers until they are all standardized. So, to be on the safe side, put a collar on your cat as well. You may save him a trip to the shelter by allowing whoever finds him to simply call you directly.

Make sure you always have a few clear, close-up and recent photos of your cat, showing his face straight on, as well as some of his entire body, especially of any identifying features. Vital for "lost" posters, photos also help identify pets at animal shelters and pounds.

If your cat doesn't return within a day or so, launch an all-out search. First, check your home very thoroughly. He may be trapped in a closet, in hollow furniture, in a hole where pipes enter the wall — anywhere a cat can fit, which can be a surprisingly small space. Check crawlspaces, under porches, outbuildings, and even the roof. Remember that sick or injured cats will often hide in a safe place to recover.

Next, go public. Ask all your neighbors, especially children, if they have seen your cat and to keep an eye out for him. Offer a reward and advertise. Place a good photo of him in the center of a poster with large, clear lettering saying "Reward," "Lost Cat," and giving your cat's breed, color, and any distinguishing marks, and a reliable phone number or two. Head to the copy center and make copies; color ones are best. Hand out posters to neighbors. Ask local store owners if you can put one in their window or at their cash register. Go far and wide; many cats are found miles from home. Take out a classified ad in your local paper repeating the information on the posters, and check the "Found" ads every day.

Find out the animal control agency responsible for your area, as well as any other shelters, pounds, humane associations and vet clinics in your area, and visit them daily. If possible, go into the stray cat department yourself. Look carefully and consult your photos: Your cat may be dirty, hidden in the back of your cage and too stressed even to recognize your voice. Leave photos of your cat with the staff, but keep visiting since many shelters are understaffed and can't check every new arrival against the "lost" list. Ask each one about any other places you should check. And don't give up! Sometimes cats turn up months after they're lost.