Cats are territorial by nature, and not automatically compatible with every other member of their species. If you wonder why Fluffy, Muffy and Mephisto won't play nice, consider how you might react if forced to share your home with incredibly annoying humans acting like they own your place. Certain felines, just like people, are Greta Garbos: They vant to be a-l-o-n-e.

One way to get a good night's sleep and reduce violence-related vet bills is to "create every possible opportunity for your cats to get along," suggests Pam Johnson-Bennett, the cat division chair for the International Association of Animal Behavior Consultants and author of Psycho Kitty.

Getting Acquainted
Start off on the right paw by introducing any new cat or kitten to your other kitties very, very slowly. Keep the new cat or kitten in a separate space with its own food, water and litter boxes, and designate a third space as a communal area that each cat can visit individually, but never simultaneously. As the cats take turns sniffing and patrolling the "communal" site, the beasts will adapt to — and eventually accept — each other's smell.

To check on integration readiness, rub an old, clean sock over the newcomer's face to sop up kitty pheromones. Then, toss the sock into the room where your longtime cat is hanging out. "If he tears it to shreds," you will need to go extra slow, says Johnson-Bennett. A smooth unification may take one day or several months, but the process will result in fewer scraps in the long run, she promises.

Next page: How to stay serenely separate