Betsy Lewin grew up in Clearfield, Pennsylvania. She always loved to draw and can’t remember ever wanting to be anything but an artist. Her mother (a kindergarten teacher) is responsible for her love of children’s books. She read to Betsy and her brother every night: Winnie the Pooh, The Adventures of Barbar, Uncle Remus and all the fairy-tale books. The illustrators Ernest Shepard and A. B. Frost were among her earliest heroes. Later on, when she started illustrating for children, Betsy realized how strongly she’d been influenced by the gentle watercolors of Beatrix Potter and the energetic line and humor of James Stevenson and Quentin Blake.

After graduating from Pratt Institute, where she studied illustration, Betsy took a job as an assistant art director at a greeting card company in New York, which lead to freelance work for other card companies. She began to write and illustrate stories for children's magazines, which became her stepping-stone into the world of children,s books. When an editor at Dodd, Mead and Company asked her to expand one of those stories into a picture book, Betsy says, "I jumped at the chance. I've been doing picture books ever since and loving every moment.";

Her love for this art form is evident in the deft and whimsical way she handles line and her bold confidence with color. She is known for illustrating both the natural world and the world of humorous picture books targeted to a younger audience.

In 2001 she was awarded the Caldecott Silver Medal for Click, Clack, Moo Cows That Type written by Doreen Cronin. This title remained on the New York Times Best Seller List for 45 weeks. The second book in this series, Giggle, Giggle, Quack also by Doreen Cronin remained on the New York Times Best Seller List for 20 weeks. The third book in the series is scheduled for publication Spring 2004 by Simon & Schuster.