How to introduce a new kitty to your cats

First: make sure all the cats are fixed! Introductions can really go awry if one or more of the cats have behavioral problems associated with being "intact" (plus, you don't want anyone getting pregnant!)

Next, the way you introduce the cats is really important. Start by putting your already-established kitty in a seperate but adjoining room to the new kitty (don't put new kitty in your established kitty's favorite room--she will feel displaced and jealous). They will most likely pick up on each other's scent, and may play with each other's paws under the door. Having them in the same house but different rooms triggers curiousity, while keeping the perceived threat-level down.

Keep a seperate litterbox, food, water, and something to scratch in the room where the new kitty is kept.

Also, rub each cat down with a towel, and place that towel in the other cats' room. This allows them to get used to each others' scent. They will also smell each other on you if you pet each frequently.

After they have discovered each other's presence, wait about 24 hours, then crack open the door between them. Let them make face-to-face introductions at their own pace. Make sure you are PRESENT when this happens, because even with this gradual introduction, they may become aggressive toward each other.

At the first meeting, give extra special attention and love to your established kitty. Don't pet new kitty or give her attention. It's likely that established kitty is already feeling territorial, and if she finds "her person" fawning over an intruder, it will just add to her negative feelings about this new family member.

Have a tin can (like a soda can) filled with coins, and taped shut, ready for their first face-to-face meeting. If any violence erupts, throw the can near the fighting kitties (not at them!). The sound will scare them and break up the fight so that you can get them to their respective areas of the house again--behind closed doors.

If there is violence at the first meeting, keep them in their seperate areas of the house for longer, and then try the gradual introductions again. They may never quite get along, but they will eventually learn to tolerate each other.

On the other hand, they may tolerate or even like each other after that first meeting--in which case, congratulations!