Cat School

At the start of the rehearsal process, performers in Cats are put through "Cat School" - essentially a boot camp in which performers learn how to evoke the movement, physicality and behaviour of actual cats. The process involves a lot of improvisational exercises, with the cast mimicking feline traits such as crawling around on all fours sniffing, scratching, and stretching. The cast then incorporate these lessons into their onstage performance so as to create a convincing anthropomorphic illusion.

"It's a really gruelling rehearsal process because it all comes from the place of being a cat. You can't really say it's jazz or contemporary; it's more cat style, which is what helps its longevity and stops it from being dated. For a trained dancer that can be exceptionally difficult because you have to let go of those restrictions and rediscover how to move, how to be flexible and nimble."

- Sharyn Winney, resident choreographer

Rehearsal process
An account of the rehearsal process for the original Broadway cast:

[...]

The next day, the cast got down to work. Nunn gave acting exercises to begin breaking down the inevitable barriers among a group of strangers. He also got them talking about cats.

"If you have a cat or known someone who has one," Nunn instructed them, "pick something the cat has done that struck you as hilariously funny and do it."

[...]

Back at the rehearsal studio, the cast went down on all fours. "Start working on cleaning yourselves," Nunn said. After rolling and sleeping and stretching like cats on the dirty floor, the actors were indeed dirty, enough so that Nunn permitted them to mime the licking motions that cats use to make their toilette.

The exercises covered the whole range of cat behavior. "You know," said Groener, "how cats can suddenly get interested in something else, or how they can get stuck on one thing for a whole hour. We also did animated cartoons: Felix the Cat, Tom and Jerry."

Finally, members of the company turned their attention to the specific cat characters they would be portraying.

[...]

Nunn, whose use of it became legend with Nicholas Nickleby, employed improvisation extensively for Cats. In character now, the various cast members were deployed in pairs, playing with each other, keeping an eye on each other. Each pair was obliged to make up a story or a situation. Then Nunn brought the pairs together into fours, insisting that they work their stories into new ones.

As the unwanted Grizabella, Buckley remained alone, out on the fringe of the action. "She was told to try to join us and we had to react to her moves," Groener said. "I would always forbid her to enter."

[...]

The cast was still down on all fours when, finally, Trevor Nunn pronounced himself satisfied. "He said it felt like a pack of cats, a family, and that was a wonderful thing," Groener recalled. "He said that, for the first time, he felt as if he were intruding."

Then Nunn told the cast to stand up and remember to keep on being cats. "We started to transfer everything to two legs," Groener said.

Meanwhile, the company was working with choreographer Lynne, who also began with exercises. "We practiced making catlike movements, getting a sort of jazz look," Groener said. "A lot of arching and what Gillian called 'naughty bottoms.' She wanted everyone to be aware of their bottoms. The Jellicle Cats think they're very special. They are sensual. They go into a frenzy under the Jellicle Moon."