When advertising copywriter Angie Dunne brought her two kittens home from the shelter last year, she already knew they got along. “The people at the animal shelter told me they really gravitated toward each other, that they played together all the time,” says Dunne. “I’d actually planned on adopting only one cat, but I was convinced that they shouldn’t be separated. Now I couldn’t imagine one without the other.”

Adopting two cats, or bringing a second kitty into a one-feline home, isn’t always easy. Los Angeles-based cat behaviorist Marva Marrow says, “Knowing how to choose a ‘pet’ for your cat will give the best odds for avoiding personality conflicts, which often show up as behavior problems, like litter box avoidance, spraying or marking, aggression and other unwanted behaviors.” Below, Marrow advises how to make a good cat match — and when not to try.

Why Two?
Simple, says Marrow. “When they’re well-matched, it’s good for cats to have companionship.” Two cats can play together, satisfying their need for physical and emotional interaction. According to the Humane Society, multi-cat household felines tend to be happier and less likely to get in trouble. They can also groom each other, keeping clean the places one cat can’t reach alone.

Which Two?

  • Choose cats or kittens with physiques and body types that mirror that of the feline already sharing your home. “Cats with similar body types have comparable activity levels, and so they complement each other,” says Marrow. For example, a good partner for a Siamese would be another “slinky” cat.
  • Don’t adopt two female cats. If you already have one girl at home, don’t get a second. “I hate to say it, but females are usually the ones who have problems with each other,” admits Marrow. “Two males get along fine, as do males and females.”
  • Make a list of your cat’s personality traits. Is your furry friend shy or social? Clingy or aloof? “Like people, cats get along better with other cats whose temperaments match their own,” says Marrow. She suggests taking your list to the shelter, and asking the employees to find the best match for your kitty.

When Two Cats Begin Sharing Your Home
When cats first cohabitate, they need to be introduced gradually and under strict supervision. The cats cannot have any access to each other when you’re not home. Marrow suggests longer and longer supervised periods of exposure filled with toys and treats to keep everybody happy. The timeline for this supervised interaction is around one month, though it may vary with different cat pairs. “You need to help them adjust slowly, so no one gets stressed,” says Marrow.

When One Is Enough
Cats need space to hide when they desire alone time, so if you don’t have much, one feline may be all you can handle. Your home should allow for the newly introduced cats to be separated — at least for the first month — when you are not home to supervise. Finally, your home should have room for a minimum of one litter box for each cat (ideally, one for each cat plus one extra).

Two final considerations are the age and health of the resident cat. The stress of bringing another pet into the home could potentially shorten the life of an elderly cat or a cat with serious health issues.

With the right pairing and introduction, two cats living together may ultimately lead more satisfying, enjoyable lives than do “single” felines. But remember, stresses Marrow, “Not all cats like all cats. You can’t just slap two together and expect them to get along.” But with the above criteria, “you and your cats can have the best chance for success.”