How to Introduce Cats: A Step-by-Step Plan

To introduce cats, keep them in separate areas at first, let them get used to each other’s scent, then let them see each other through a barrier, and only then allow short, supervised time together. The step-by-step part commonly takes from about a week or two to several weeks, and a settled relationship can take much longer, often months. Let the slower, more worried cat set the pace.

The plan below follows the staged approach used by Cats Protection, International Cat Care, PAWS (ASPCA guidance), Best Friends Animal Society, and American Humane. It is a general guide, not an individual behavior plan.

Stage 1: Prepare a separate room for the new cat

The newcomer starts in a room of their own. The resident cat keeps the rest of the home and its familiar routines.

Choose a quiet room with a door that closes reliably, such as a spare bedroom. Cats Protection suggests a room the resident cat does not use.
Set it up before arrival with food, water, a litter box, a bed, a scratching post, and places to hide. Our new cat room setup guide walks through the layout.
Use new items or the new cat’s own items, not the resident cat’s belongings, as International Cat Care advises.
Keep spending time with your resident cat. Best Friends recommends spending more time with your existing cats so they see the newcomer as something that improves their lives.

Signs it is going well: the new cat eats, uses the litter box, explores the room, and rests. The resident cat keeps its normal eating and litter habits.

Signs to slow down: hiding most of the time, a reduced appetite, or a lot of vocalizing in either cat. Best Friends advises contacting your veterinarian if signs of stress last more than several days or a cat stops eating.

Stage 2: Swap scents

Cats learn a lot by smell. This stage lets them meet each other’s scent before they meet in person.

Gently wipe a soft cloth or sock around one cat’s cheeks, then place it where the other cat can choose to investigate or ignore it. Cats Protection suggests placing it in the middle of the floor.
Swap a piece of bedding between the cats. International Cat Care recommends making sure each cat still has enough bedding of its own.
Swap rooms. PAWS suggests switching the cats’ locations after two to three days so each can explore the other’s area. The resident cat is confined while the newcomer explores, then they switch back.
Repeat until neither cat reacts much to the other’s scent.

Signs it is going well: sniffing the cloth or bedding calmly, rubbing on it, or ignoring it.

Signs to slow down: International Cat Care notes that if a cat avoids or hisses at the swapped bedding, you should slow down. Keep swapping for longer before moving on.

Stage 3: Feed on opposite sides of a closed door

The goal is to link the other cat’s presence with something pleasant.

Place each cat’s food bowl on its side of the closed door. Best Friends recommends starting several feet from the door.
Move the bowls a little closer to the door over several meals, only as both cats seem comfortable.
Offer a favorite treat near the door if a cat is hesitant. American Humane suggests a tasty snack if a cat will not eat at the door.
Play with each cat near the door. PAWS notes the cats may eventually paw at toys under the door.

Signs it is going well: both cats eat normally near the door and show relaxed curiosity.

Signs to slow down: growling or hissing at the door, refusing food, or changes in litter box use. American Humane lists these as signs to give that cat more time. Move the bowls back to a distance where both cats eat calmly.

Stage 4: Allow visual contact through a barrier

Two cats in a dim doorway keeping their distance, a cream cat sitting back and a tabby crouched near the threshold — Two cats watching each other from a distance across a doorway. Photo: Patrick / Unsplash

PAWS suggests moving to this stage after about a week, assuming there is no hissing or growling at the door. Some cats need longer.

Use a barrier the cats cannot get past, such as a screen door, a door propped open a couple of inches, or a baby gate. American Humane suggests stacking two gates, because many cats can jump one.
Start each cat a few feet back from the barrier. Keep sessions short.
Let each cat choose whether to approach. Do not carry a cat up to the barrier.
Pair the sessions with something pleasant at a comfortable distance, such as tossed treats or gentle play. PAWS and Best Friends recommend treats and play. International Cat Care cautions that some cats find eating or playing in view of another cat stressful, so watch how your cats respond and increase the distance if either cat stops eating or playing.
End each session calmly, before either cat becomes tense.

Signs it is going well: relaxed posture, looking and then looking away, sniffing through the barrier, eating or playing nearby.

Signs to slow down: staring, growling, hissing, flattened ears, a puffed tail, or swatting at the barrier. Close the door, let both cats calm down, and repeat the previous stage for a few days.

Stage 5: Supervised time together

Two cats lying relaxed a short distance apart on a carpeted floor in warm afternoon sunlight — Two cats resting calmly in the same sunny room, a little apart. Photo: Muhammad Khawar Nazir / Pexels

Choose a calm time. PAWS suggests after a meal or play.
Bring both cats into a large room, ideally with one person per cat. Best Friends suggests each person play with, pet, or give treats to one cat so the cats are occupied rather than focused on each other.
Make sure each cat has an escape route and a high place to go. Cats Protection stresses that both cats need an exit or a high spot.
Keep the first sessions short and end them on a positive note. Gradually lengthen them over multiple sessions.
Keep the cats separated whenever you cannot supervise them. American Humane recommends this until they are clearly getting along.

Signs it is going well: both cats move around freely, eat, use the litter box, and rest in the same room without chasing or blocking each other.

Signs to step back: stalking, chasing, blocking a doorway or litter box, or one cat hiding most of the time. Cats Protection lists blocking hallways, doors, or litter trays, and pushing another cat off resting places, as signs of bullying.

Stage 6: Unsupervised time

Start with short periods while you are at home, as International Cat Care suggests, just a few minutes at first.
Lengthen the time gradually over days or weeks.
Keep separate resources in different locations so neither cat has to pass the other to eat, drink, or use the litter box.
Continue to give the newcomer access to their original room as a retreat.

Signs it is going well: calm coexistence, normal appetite and litter habits, and voluntary time near each other.

Signs to step back: any fight, a cat that stops using shared areas, or repeated chasing. Return to supervised sessions.

How long does it take for cats to get along?

There is no fixed timeline, but sources give a general picture:

International Cat Care says the new cat’s settling-in period alone usually takes several days to a week or two.
PAWS, using ASPCA guidance, suggests visual contact after about a week if there are no signs of aggression at the door.
Cats Protection says the whole introduction process could take weeks, and that the time between steps is often much shorter with kittens.
PAWS notes that most cats take eight to 12 months to develop a friendship with a new cat, and that some cats never become close friends. Many learn to avoid each other peacefully instead.

Factors that affect the pace include each cat’s personality and past experience with other cats, the age difference, and the layout of the home. Best Friends notes that cats who have previously lived with another cat are more likely to get along with other cats. PAWS adds that individual personality matters more than sex, age, or size.

Body language: normal hissing vs warning signs

Some hissing early on is common. American Humane notes that some hissing or swatting is expected at the first meeting and that cats often settle it themselves. Occasional hissing that eases over the sessions is usually less concerning than hissing that grows more intense.

Signs that a cat is more than uneasy, based on the ASPCA’s guide to cat aggression:

Offensive posture: stiff, upright stance, direct stare, hackles up, constricted pupils, moving toward the other cat, growling or yowling.
Defensive posture: crouching, head tucked, tail wrapped around the body, ears flattened sideways or back, dilated pupils, open-mouthed hissing or spitting.
Overt aggression: swatting, biting, scratching, fighting, or shrieking.

If you see these signs, end the session calmly and go back a stage. The ASPCA also warns that a cat aroused by seeing another cat through a window or door can redirect aggression to whoever is nearby, so give an agitated cat time and space.

What to do if the introduction goes wrong

Go back to the last stage where both cats were relaxed and stay there longer.
If a fight starts, separate the cats without using your hands. The ASPCA advises against breaking up a cat fight directly or approaching an agitated cat. International Cat Care suggests a calm distraction, such as calling the cat’s name, then leading each cat away.
Lead each cat to a quiet room and let them calm down before trying again another day.
Never punish either cat. International Cat Care notes that punishment increases fear, and the ASPCA says painful punishment can worsen fear and territorial aggression.
Book a veterinary visit if a cat stops eating, stops using the litter box, or behaves aggressively. The ASPCA recommends checking cats with aggression problems for underlying medical issues, such as pain.
Ask your veterinarian about a qualified behavior professional if problems continue. International Cat Care and Best Friends both recommend this step.

American Humane notes that if a fight injures or traumatizes a cat even after following the steps, the pairing may not work. Most introductions do not reach this point, but it is worth knowing in advance.

Resources in a multi-cat home

Competition over resources is a common source of tension. Cats Protection and International Cat Care both recommend:

One of each key resource per cat, plus one extra: litter boxes, food and water bowls, beds, scratching posts, and hiding places.
Resources spread across different locations, not lined up in one spot.
Separate feeding areas, ideally in different rooms.
Vertical space, such as shelves and cat trees, plus hiding spots at floor level. PAWS notes that frightened cats tend to hide under things.
Food, water, and litter boxes placed out in the open so a cat does not feel trapped while using them.

Our multi-cat resource layout guide shows how to map these across your home.

FAQ

How long should I keep a new cat separated? American Humane suggests at least a few days in a separate room. Many cats need longer, and International Cat Care says settling in usually takes several days to a week or two.

Is it normal for my cat to hiss at the new cat? Some hissing is common early on. It becomes a concern if it gets more intense, comes with stalking or fighting, or does not ease over time.

Can I introduce cats faster? Going faster raises the risk of a bad first impression. PAWS notes that aggression at a first meeting may set the tone for the relationship. Kittens often move through the steps more quickly.

What if my cats never get along? Some cats never become friends but learn to share a home by avoiding each other. If there is ongoing fighting or one cat hides most of the time, talk to your veterinarian about a qualified behavior professional.

Sources and editorial notes

Timelines are typical ranges from the sources above, not promises. Every pair of cats is different. This guide does not replace an individual assessment by your veterinarian or a qualified behavior professional.

Prepared with AI assistance and reviewed against the sources above.