Kimberly "Kim" Baker (born February 21, 1996) is the eighth child of the Baker family.
In the first film, she is seven years old and very clever and very smart like her twin sister, Jessica. She is frequently involved in her sister Sarah's pranks.
She and Jessica are told that they must stop correcting their teacher in front of the class. Kim is quite serious but enjoyed taking part in the prank against Hank. When she, Jessica, Jake, Mike and Mark all start at their new school she is seen holding Jessica and Jake's hands. Kim attends all of her fathers football games and is disappointed when she misses one, especially as it was her fathers last one. She went to Dylan's birthday party, along with her twin Jessica, Sarah, Mike, Mark, Jake, and Henry. Kim preffers blue and Jessica likes pink.
In the second film Kim is nine years old and more mature. She still is a genius and now more focused on computers and logic rather than the immaturity she shared with her twin sister. She and Jessica presumably make friends with the Murtaugh twins Lisa and Robin and use their Internet hookup to study for a decathlon. Kim tries very hard with the Labor Day Cup training, and nearly hits Bud on the head with a volleyball. She was part of an egg toss challenge with Jessica, but they lost because Jessica didn't catch the egg. She also was part of a canoe race with her family. Kim is unbelieving when she finds out that her father was spying on Sarah's hang out, and she says "I can't believe you did that." Kim seems very fond of her nephew Tom in the last scene as she waves goodbye to him when he, Nora and Bud leaves.
Kim Baker is played in both films by Morgan York.