considerations to set you up for success
Resources available
It’s important to consider the availability of resources. First off, consider the amount of space in the home – not just square footage, but space that is usable for the cat. That includes vertical space like shelves and cat trees. Consider funds available for food and supplies, and veterinary expenses. And consider the amount of time and energy you have to give.
People in the home & resident pets
The other thing that’s important is the personalities and energy levels of everyone in the home – the people and any resident pets.
Think about your lifestyle and what you want your relationship with the new cat to look like. Make sure you have realistic expectations. How important is it to you that the cat be a cuddly lap cat? Remember, every cat is an individual. Some cats are more cuddly, and some cats are more independent. But make no mistake, cats aren’t low-maintenance pets! There really is no such thing.
If you can’t keep up with a lot of playful energy, don’t adopt a kitten. And while we’re on the subject of kittens, don’t make the mistake of adopting a kitten as a companion for a senior cat. That’s like adopting a toddler for Grandma. That’s not going to set them up for a good relationship.
If you’ve recently lost a cat, remember to give the new cat a fresh start. They can’t replace the one you lost. Every relationship is unique.
Feline social structure
Territory and hunting
Cats are often thought of as antisocial, but that isn’t really accurate. Cats are solitary hunters. Their prey isn’t big enough to share. So each cat needs to establish their own territory for hunting. Cats mark their territories using scent and pheromones. In this way, they leave messages for each other, so they can communicate and prevent direct conflict (iCatCare, n.d.).
A cat’s territory is the area they will actively defend. Within the territory is the core territory, where the cat feels safe enough to play, eat, groom, and sleep, and potentially enjoy social interaction.
Cats’ territories may overlap, with neutral areas in between. If an unfamiliar cat enters another cat’s territory, they are met with a warning: staring, hissing, and growling. If that doesn’t work, the resident cat may chase and attack the intruder (iCatCare, n.d.).
Colonies
Colonies form in areas where food is available (Crowell-Davis et. al, 2004).
Cats from the same colony will approach each other with a friendly tail-up signal, nose-touch, and walk past each other, rubbing along each other’s sides (allorubbing). Then, they might sniff each other’s rear ends. Sometimes, they will walk side-by-side with tails entwined.
Cats that are from the same colony will scratch and rub their cheeks on objects in the area, creating a “group scent.”
The social behavior of free-roaming cats is quite variable. Some colonies have groups with strong social bonds, while others are more loosely associated (Vitale, 2022).
When cats form social groups, they aren’t random. Groups are commonly made up of related queens (mother cats) who share the work of caring for kittens. Group living offers greater protection from intruding males and predators. Male cats usually live on the periphery, with large territories that overlap with other cats. (iCatCare, n.d.).
Preferred associates
Cats form friendships with other cats they like to be close to. Scientists call them “preferred associates” (Crowell-Davis et. al, 2004). A cat’s preferred associates are most often relatives or other familiar cats (Vitale, 2022). With the exception of breeding adults, there is no effect of gender on which cats are preferred associates. With spayed and neutered cats, gender doesn’t matter (Crowell-Davis et. al, 2004).
Cats who are preferred associates often groom each other and sleep together, in close physical contact.
It's not about dominance
Cats don’t have a rigid social structure.
In the field of animal behavior, the word “dominance” means having priority access to resources. The idea of dominance doesn’t really apply to cats. Some cats may be dominant in different situations, meaning that they get priority access to certain resources, but these relationships are always in flux. With cats, there is no fixed dominance hierarchy.
Physical fights within a group are infrequent. Instead, cats use body posturing (such as lowering the ears slightly, turning the head away and leaning back) to diffuse tension and avoid fighting. When conflict does occur, it’s usually when male kittens reach sexual maturity. They get kicked out of the group and have to go and establish their own territory (iCatCare, n.d.). This serves to prevent inbreeding. Interactions between intact toms are mostly characterized by avoidance and tolerance, sometimes aggression.
Outsiders are met with aggression. If a non-colony member is persistent, they may eventually be integrated into the group, but only after many interactions (Crowell-Davis et. al, 2004).
Cat personalities
Individual cats have different personalities and different levels of sociality.
A cat’s personality is shaped by genetics and their learning history (Finka, 2022). It includes traits like: boldness vs. fearfulness, sociability toward other cats, sociability toward humans, and activity level.
Socialization
The period from two to seven weeks is the critical socialization period for kittens. During that time, they learn how to interact with the world, and they form their attitudes toward other cats and toward humans.
When it comes to pet cats, some become stressed from living with other cats, while others are stressed when they live without feline companions. Cats have different levels of sociality to humans as well. Some form strong bonds with humans (Vitale, 2022).
Kittens learn from their mother how to interact with humans. They will socialize to humans more readily if their mother is calm in the presence of humans (Vitale, 2022).
Kittens who grow up without their mother or without littermates miss out on important learning experiences that happen during adolescence and, so, they won’t learn how to interact appropriately with other cats. Their lack of social communication skills can show up as excessive fear or aggression (Crowell-Davis et. al, 2019).
Choosing a cat to adopt
If you plan to have a multi-cat home and want to make a successful match, activity level is more important than age. It may actually be the most important factor.
That said, kittens are easier to introduce to each other. The disadvantage is you don’t really know their personalities. When you adopt a kitten, they haven’t experienced much of the world yet. Their personality is still forming, so you don’t really know what you’ll get. Will the kitten grow up to be a lap cat, a couch potato, or an adventurous explorer…?
Cats reach social maturity somewhere between a year and a half and four years old. That’s when their personality is fully developed. Of course, they can still learn and change their behavior, but their essential personality stays the same.
When you adopt an adult cat, you get to see more of their personality. But often, much of their backstory is a mystery. More on that later.
Other things to consider…
Some breeds are known for their activity level. Bengals, for instance, are high-energy, agile and curious. Ragdolls are the opposite. They are known for their docile temperament. A cat’s breed doesn’t need to be an important consideration, unless you’re looking for either extreme. Most cats are mixed breeds. If you are looking for a specific breed, it’s important to look for a reputable, responsible breeder.
If the cats are spayed and neutered, gender doesn’t matter. Size could be a factor if the more assertive cat is much larger.
Judging a cat’s personality can be highly subjective. Things like a cat’s gender, breed, and coat color can impact how we perceive their personality, and we can’t help but be influenced by our own personality and previous experiences. For example, if I grew up with two cats in my family, a friendly orange male and a shy Siamese female, I might think that orange cats are more friendly than Siamese cats, and that male cats are more outgoing than females. And that may or may not be true of the new cats I meet. It’s worth taking a closer look at your assumptions and biases, so you can really see each cat as an individual.
It can be hard to judge a cat’s personality when you meet them in a shelter. Shelters are stressful environments, so the cat is probably going to be scared, not showing their true personality and their full range of behaviors.
Even in a foster home, it can be hard to know for sure. For example, just because the cat lived peacefully with a dog in the foster home, there is no guarantee the cat will get along with all dogs in any context. Animals (humans included) tend to generalize negative experiences when our brains are in survival mode. Meaning if a cat is chased by a dog in their previous home, the cat will probably assume that all dogs are scary (better safe than sorry). But if they have a positive experience, it doesn’t necessarily translate. Getting along with one dog doesn’t mean all dogs are OK. Maybe the previous dog was an older dog who slept most of the time and ignored the cat, but the new home has a puppy. That’s not the same!
If you take in a cat who was previously living outdoors, it can be even more challenging, especially if the cat is undersocialized and doesn’t trust humans. With cats who are undersocialized, it takes longer for them to settle in and feel safe in the home, before you can fully see their personality.
One of the best ways to get to know a cat is through a foster-to-adopt program. By fostering the cat, you get to see how they act in your home environment. After some time, you could introduce them to your resident pets to see if they get along.
Realistically, the best we can do is to find out what is known about the kitten or cat’s background and make the best judgement that you can. Avoid obvious mismatches. A cat who is bold and has low sociability toward other cats might become a bully in a multi-cat household.
Multi-cat homes
When it comes to multi-cat homes, a variety of factors may influence whether cats will get along in the long run.
The initial introduction can be the deciding factor.
A significant number of cats will fight when a new cat is brought into the home. In one survey, about half of the multi-cat households reported fighting between cats when the new cat was introduced. Cats that fought when they first met (biting or scratching) were more likely to still be fighting up to a year later (Levine et. al, 2005). Another study found that, in multi-cat households where conflict was reported, over 73% noted conflict signs from the very beginning when introducing the cats (Elzerman et. al, 2019).
That’s why it’s so important to set up for success from the start!
It’s important to remember that free-ranging cats can choose to leave an undesirable social situation, whereas companion cats (especially indoor-only cats) cannot. Cats living in a multi-cat home have their roommates chosen by their caregivers. They don’t automatically form bonded social groups (Rodan et. al, 2024).
Social groups of cats tend to work best when the members are familiar with each other and there is no competition for resources (iCatCare, n.d.). With that in mind, people who wish to have a multi-cat household might do better by adopting littermates, or a mother cat with one or more of her kittens (Crowell-Davis et. al, 2019).
A gradual introduction process is recommended, especially when introducing mature cats (5 + years) to each other (Hoff et. al, 2025). When I say “gradual,” expect it to take weeks or months, not just a few days. (You may have been lucky with cats in the past, but quick introductions are the exception, not the rule, with adult cats.)
“[T]ypically, intercat tension within a home occurs because there is competition over resources,” or something is threatening the social relationships within the group – introduction of a new cat, territorial invasion by an outdoor cat, or pain or sickness (Rodan et. al, 2024). One study found that 97.5% of aggressive encounters centered around food (Vitale, 2022). This is one reason why using mealtime for introductions is a bad idea! I’ll talk more about that in the next article.
To prevent conflict, ensure that there are plenty of resources (food and water, litter boxes, scratching posts, elevated perches, toys and play areas, beds / resting areas, hiding places, etc.) spread out around the house, to eliminate the need for competition. Plenty of resources means the number of cats plus one, ideally.
Each cat will establish their own territory. It’s important that resources be spread out around the house so that each cat can access everything they need without having to cross through another cat’s core territory. They can interact in the neutral areas if they choose, or they can avoid the other cats if they prefer (Crowell-Davis et. al, 2019 and iCatCare, n.d.).
Summary - graph
To maximize the probability of a successful introduction, it’s important to try to choose cats with compatible personalities, and to ensure that there are plenty of resources spread out throughout the home, so there’s no need for competition.
How do you know if the cats have a good relationship?
Positive signs
When two cats greet each other with tails up and rub against each other and head-butt against each other (called bunting), they often allogroom and sleep in close contact with one another, that means they have a good relationship, and you shouldn’t be too concerned if there is an occasional mild negative exchange, such as swatting or nipping each other at the end of a grooming session.
Negative signs
Staring at each other with tails lashing, one cat chasing the other (not taking turns), hissing and screaming, fur flying and visible scratches are clear signs of a negative relationship.
When cats are fighting like this, even if it’s infrequent, it’s a serious safety risk. If one of the cats gets injured, or if you get injured trying to get between them – please don’t, by the way! use a heavy blanket or a piece of cardboard instead – , you could end up with an expensive medical bill. It’s best to separate them, before the situation gets worse.
Something in between
A strong negative relationship is often obvious, but a slightly negative or neutral relationship is harder to identify. If the cats sleep near each other but aren’t actually physically touching, they don’t often nose-touch, head-butt (bunt), or rub against each other, and their interactions are rarely mutual, they may have a neutral relationship. That’s fine if they mostly avoid each other. However, if one cat often corners another and there is hissing and growling, then there is likely tension in their relationship, which can be harmful for their well-being in the long run (Gajdoš-Kmecová et. al, 2023).
Playing or fighting?
Cats play rough, so it can be hard to tell if they are playing or fighting. Like any relationship, it’s not black & white. It’s definitely a spectrum, and we need to look at the big picture – considering behavior patterns in context and over time – to really be able to tell.
If they take turns chasing and there is no vocalization, and especially if you see a butt-wiggle, then it’s most likely play. Another key indicator is if the cats go back for more afterward, or if they seem to stay agitated. If they are eager to get back together, then they have a good relationship.
Be mindful that sometimes it’s a game for one cat, but it’s stressful for the other. Or, sometimes, what starts out as play can get a little carried away. When that happens, the cats can communicate that they’re done playing. You don’t need to be concerned unless one cat hisses and the other cat won’t back off. That could mean that that cat needs to learn some communication skills, perhaps through training.
What to do if your cats have a negative relationship
If you suspect your cats have a negative relationship, whether that’s slightly negative or strongly negative, you have some options.
- Reach out to a cat behavior professional who can help you work through a reintroduction process.
- Decide to keep the cats in separate parts of the home long-term.
- Find a new home for one or more cats.
Even when we try our best to make thoughtful matches, it doesn’t always work out. Sometimes, bonded pairs break up after a stressful move to a new home. Other times, cats who were once best friends will have a falling out once they reach social maturity. (That happened for my cats, Linus and Jasper.)
When that happens, we need to think about what will give all the cats the best welfare. That might mean separate territories within the home, or finding a new home for one of the cats. It’s not good for anyone to keep living in a stressful home environment. Although it’s not the outcome we would wish for, it’s still a happy ending when the cat has the opportunity to thrive in a different environment.
Help with a cat introduction or reintroduction
If you want help with a cat introduction or you want to improve your existing cats’ relationships, you can work with me. Click the button below to schedule a meet & greet to get started!
References
- Crowell-Davis, S. L., Curtis, T. M., & Knowles, R. J. (2004). Social organization in the cat: A modern understanding. Journal of Feline Medicine and Surgery, 6(1), 19–28. https://doi.org/10.1016/j.jfms.2003.09.013
- Elzerman, A. L., DePorter, T. L., Beck, A., & Collin, J.-F. (2019). Conflict and affiliative behavior frequency between cats in multi-cat households: a survey-based study. Journal of Feline Medicine and Surgery, 22(8), 1098612X1987798. https://doi.org/10.1177/1098612×19877988
- Finka, L. R. (2022). Conspecific and Human Sociality in the Domestic Cat: Consideration of Proximate Mechanisms, Human Selection and Implications for Cat Welfare. Animals, 12(3), 298. https://doi.org/10.3390/ani12030298
- Gajdoš-Kmecová, N., Peťková, B., Kottferová, J., Halls, V., Haddon, C., de Assis, L. S., & Mills, D. S. (2023). An ethological analysis of close-contact inter-cat interactions determining if cats are playing, fighting, or something in between. Scientific Reports, 13(1), 92. https://doi.org/10.1038/s41598-022-26121-1
- Hoff, A., Czycholl, I., Lund, T. B., Mills, D., Serpell, J., & Sandøe, P. (2025). Introducing new cats to multi-cat households: Results of a representative survey of Danish cat owners. Applied Animal Behaviour Science, 293, 106855. https://doi.org/10.1016/j.applanim.2025.106855
- International Cat Care. (2025). The social structure of cat life. Icatcare.org. https://icatcare.org/articles/the-social-structure-of-cat-life#understanding-the-social-structure-of-cats
- Khoddami, S., Kiser, M. C., & Moody, C. M. (2023). Why can’t we be friends? Exploring factors associated with cat owners’ perceptions of the cat-cat relationship in two-cat households. Frontiers in Veterinary Science, 10. https://doi.org/10.3389/fvets.2023.1128757
- Levine, E., Perry, P., Scarlett, J., & Houpt, K. A. (2005). Intercat aggression in households following the introduction of a new cat. Applied Animal Behaviour Science, 90(3-4), 325–336. https://doi.org/10.1016/j.applanim.2004.07.006
- O’Brien, Carolyn. “Behavioral Dynamics in the Multicat Home.” Clinician’s Brief, 18 Feb. 2026, www.cliniciansbrief.com/article/behavioral-dynamics-multicat-home-guide. Accessed 27 Mar. 2026.
- Ramos, D. (2019). Common feline problem behaviors: Aggression in multi-cat households. Journal of Feline Medicine and Surgery, 21(3), 221–233. https://doi.org/10.1177/1098612×19831204
- Rodan, I., Ramos, D., Carney, H., DePorter, T., Horwitz, D. F., Mills, D., & Vitale, K. (2024). 2024 AAFP intercat tension guidelines: recognition, prevention and management. Journal of Feline Medicine and Surgery, 26(7). https://doi.org/10.1177/1098612×241263465
- Trevorrow, N. (2015). Behaviour matters. https://www.cats.org.uk/uploads/documents/Behaviour_-_Friend_or_foe.pdf
- Vitale KR. The Social Lives of Free-Ranging Cats. Animals (Basel). 2022 Jan 5;12(1):126. doi: 10.3390/ani12010126. PMID: 35011232; PMCID: PMC8749887