Maine Coon Breed Standards
It is common on cat websites to find quite a few people asking if their rescue cat is (part) Maine Coon, and many rescue/shelter organizations tend to list any good-sized, longer-haired cat as "Maine Coon."
To be a true Maine Coon, of course, the cat must be descended from only registered Maine Coon cats, so it is impossible to know for certain with most rescue cats.
It may be possible to make some judgement about whether a cat might have Maine Coon background by looking at its physical appearance, but this is usually difficult from one or two photos. Unfortunately, this is what people generally do: post one slightly blurry photo showing only part of their cat and ask if its Maine Coon. Making a determination from that sort of limited view is impossible.
I would suggest that people wondering whether their cat might have some Maine Coon in it try to study the breed standard, and see how their cat compares. One of the best sources for photos of what Maine Coons should and should not look like are some seminars prepared by Beth Hicks (one of the important early Maine Coon breeders, who you can read more about here:
Look at the TICA and CFA seminar links to PDFs:
Another nice page quickly showing key breed characteristics is:
It should be noted that while "lynx tips" are common in Maine Coons, they are not universal (and not required by the standards). Furthermore, domestic cats other than Maine Coons can have this feature.
Beyond physical appearance, Maine Coons should have very "small" voices given their size (they tend to tallk more quietly/softly and at a higher pitch than their size would lead one to expect). They generally do not make a typical cat "meow" sound, but instead more what people tend to call a chirp. A "trilling" sound can also be fairly common (usually used to greet particular special people). Many Maine Coons are are quite talkative (though other cats can be too).
Then there is their behavior. Maine Coons are generally very sweet, affectionate, and extremely people oriented. Of course with a rescue cat, it may be difficult to know their true personality until they have lived with you for six months to a year. Many MCs are not lap cats, but they will follow their humans around the house much of the day, keeping very close. People often describe Maine Coons as "dog like" in that they are nothing like the aloof animals many think all cats are.
- krzy4katz, katimae, AxsMan and 1 other like this