As described in Adopting the Right Cat for You, set up a room as a home base for your new cat—this will allow for a gradual introduction to the family.

For the first 72 hours, do nothing. It is important to allow your new cat to become accustomed to her surroundings. Your new cat is not only acclimating to home base, she also is using her fine-tuned senses to discover what is beyond the closed door of her home base, including resident cats. After 72 hours, begin introducing the cats to each others' scents. First, leave a blanket or towel in the home base for the new cat and another on your resident cat's favorite sleeping spot. After they each have spent time sleeping on the blanket or towel, exchange the linens. This scent introduction will help your cats get used to each other and will help improve the eventual face-to-face meeting.

While the cats are becoming used to each others' scents, create positive experiences for them while they are still safely separated. Feed the cats on either side of the closed home base door. Get a feather toy and encourage play under the door. By creating positive experiences, you send the message that another cat is a good, fun friend to have in the house.

After a week of allowing your new cat to acclimate to home base, it is time to switch the cats' living areas. Let your new cat explore the rest of the house while your resident cat stays in home base. Be sure to not let the cats meet while you are swapping rooms. After a few hours of exploration, you can return the cats to their original spaces.

After about two weeks, it is time to start introducing the cats. Clip both cats' nails to lessen the chance of injury. Place a treat (a plate of wet food or some kind of natural cat treat) outside of the home base door and place another treat down the hall from the door, but still in sight of home base. Lure your resident cat to the treat down the hall, and while she is enjoying the treat, open the door to home base and allow the new cat to enjoy her treat. By allowing the cats to see each other while enjoying good food, you are helping them associate rewards with the other cat. After they have finished their treat, place the new cat back in home base. The next day, repeat the above step, but this time place the plates a couple of feet closer together. Continue this process until the cats get close enough to meet face-toface. It is important not to interfere when they meet. It is normal for cats to hiss, howl, posture, and swat when they first meet. In the unlikely event that they do begin to fight, do not pick up either cat. Put a towel or blanket between them to block their view of each other and try to corral one to a safe place. You will need to spend more time creating positive experiences before introducing them face-to-face again. After the cats have spent time together without conflict, gradually increase the amount of time the cats are out together. After they have spent several hours harmoniously sharing the same territory, several times in a row, you can leave them alone together.

Remember to be patient as the process of introducing cats can take time, but in most cases, cats will learn to coexist peacefully. And in many cases, cats can become life-long friends.