Cats like stability so an environmental or social change may have a pronounced effect on their behavior. Your cat will adapt, but it may take some time.

Chances are your cat will react to a newcomer by distancing herself. She may hide for a few days refusing to acknowledge the newcomer, or she may act up in an attempt to persuade the newcomer to retreat. Here are a few tips to ease the transition:

• Give your new cat an area where she can retreat if she becomes threatened.
• Putting her in a spare room with the door closed for the first few days will give both cats the chance to adjust to each other's scents without hurting each other.
• Give your newcomer a litter box in her area along with food and water.

A kitten is an ideal choice, but should you want to introduce an adult cat, try to find one that has lived with other cats. A cat that is similar in age and sex to the resident cat will be accepted more readily.

In general, the following combinations in a multiple cat household seem to work best: two kittens; a mature, neutered cat and kitten; or two mature neutered cats (either two females or a male and a female). The most volatile combination seems to be two un-castrated mature male cats.

Consider your current cat's personality before introducing a new cat. An active cat is more likely to accept a new kitten. A quieter, more reclusive cat might prefer a mature, adult cat as a companion.

If your cats exhibit personality conflicts, you can reduce the tension between family felines by making sure each cat has enough personal space and personal possessions to fulfill her needs.

To avoid territory conflicts between cats, consider placing litter boxes in various locations throughout the house to avoid the exclusion of one cat from another cat's territory.

Keep scratching posts and beds in several locations to accommodate all the cats in your household.