Why do cats "knead" your lap/the surface they are sitting on?

Well there is a lot of debate out there the most common idea is that this is what a kitten does before it nurses. It 'kneads' the mother's nipple area. Perhaps that's a stimulation for the milk, I don't know. But some cats never get rid of this habbit. So most people find it a sign of happiness and contentment. Afterall, a kitten won't nurse if it's angry.

Cats do that to put their scent on you. There are scent glands in their paws that excrete something that we as humans can't detect, and they are marking you their territory in effect. Cats adopt humans, not the other way around. They want to make sure that any other cats in the area know that you're their's. It's like when they scratch furniture. They are not only sharpening their claws, but putting their scent on it to warn others away. Or when a male cat sprays his nasty smelling odor around the house. That's usually because he can smell another male around the area, and wants to let him know that he's there.

When I owned a chinchilla Persian (think of the Fancy Feast commercial cat), I, too always wondered what the "kneading" action was all about, but it wasn't until I read a book about cats that this is a "hey, I'm happy" reflex that cats develop when they are kittens and are still drinking their mother's milk. The cat grows up and goes on to eat canned and dry cat food, but he/she never outgrows the kneading reflex.

my Kitty does that alot... i think she is just preparing to sleep... she's like that... massaging, then sleep on that after... its sooo funny to watch... ;)