Leo Lionni (May 5, 1910 - October 11, 1999) was an author and illustrator of children's books. Born in the Netherlands, he moved to Italy and lived there before moving to the United States in 1939, where he worked as an art director for several advertising agencies, and then for Fortune magazine. He returned to Italy in 1962 and started writing and illustrating children's books. In 1962 his book Inch by Inch was awarded the Lewis Carroll Shelf Award.
Lionni's father was a Sephardic Jew who worked in the diamond business and his mother was an opera singer. He grew up in a house filled with his uncle's art collection. He lived within short walking distance of the two great museums in Amsterdam, the Rijksmuseum, and the Stedelijk Museum.
He married Nora Maffi, the daughter of the founder of the Italian Communist Party, and they had two sons, and later, grandchildren by both sons.
Leo Lionni died October 11, 1999, at his home in Tuscany, Italy, at the age of 89.
From 1931 to 1939 he was a well known and respected painter in Italy, where he worked in the Futurism and avant-garde styles. In 1935 he received a doctorate degree in economics (1935) from the University of Genoa. During the later part of this period Lionni devoted himself more and more to advertising design.
In 1939 he moved to Philadelphia and began full-time work in advertising, at which he was extremely successful, acquiring accounts from Ford Motors, and Chrysler Plymouth, among others. He commissioned art from Saul Steinberg, the then neophyte Andy Warhol, Alexander Calder, Willem de Kooning, and Fernand Léger.
In 1948 he accepted a position as art director for Fortune, which he held until 1960.
In 1960 he moved back to Italy, where he began his career as a children's book author and illustrator. Lionni produced more than 40 children's books. He received the 1984 American Institute of Graphic Arts (A.I.G.A.) Gold Medal and was a four-time Caldecott Honor Winner—for Inch by Inch (1961), Swimmy (1964), Frederick (1968), and Alexander and the Wind-Up Mouse (1970). He also won the Deutscher Jugendliteraturpreis in 1965.
Author & Illustrator 
Leo Lionni used a variety of art materials in his work. He would usually draw pictures as he would tell stories to his grandchildren, however on that long train ride he had no drawing materials. Instead, he tore out circles of color from a magazine to help tell his story of little blue and little yellow using lots of splotches of color. This experience led him to create his first book for children.
Lionni became the first children’s author/illustrator to use collage as the main medium for his illustrations. Reviewers such as Booklist and School Library Journal have said that Lionni’s illustrations are “bold, sumptuous collages” that include “playful patches of color” and that his “beautifully simple [and] “boldly graphic art [is] perfect to share with very young children”. Book World said that “the translucent color of the pictures and the simplicity of the text make a perfect combination”.
Lionni uses more earth tone colors in his illustrations that are closer to the actual colors of the objects found in nature. In his book, Inch by Inch, he uses realistic shades of brown and burnt orange in his collage of a robin. The tree branches are shades of brown with dark green leaves. The inchworm in the story is a muted green that resembles the color of the leaves. The bright colors in this book are found in the hummingbird and the toucan who the inchworm meets along his way. One of the most consistent characters to be found in Lionni’s books are mice, such as the star character in his book, Frederick and Alexander in the Caldecott Honor Book, Alexander and the Wind-Up Mouse. The mice in his books are always shades of gray or tan. Lionni's illustrations have been compared to those of Eric Carle. Both of these author/illustrators often employed animals, birds, insects and other creatures found in nature to tell a story about what it is to be human.
Selected works 
- Alexander and the Wind-up Mouse
- The Alphabet Tree
- The Biggest House in the World
- A Busy Year
- A Color of His Own
- Colors to Talk About
- Cornelius: A Fable
- An Extraordinary Egg
- Fish is Fish
- A Flea Story
- Frederick (named by the National Education Association one of its "Teachers' Top 100 Books for Children" based on a 2007 online poll)
- Geraldine, the Music Mouse
- The Greentail Mouse
- I Want to Stay Here! I Want to Go There!: A Flea Story
- In the Rabbitgarden
- Inch by Inch
- It's Mine
- Let's Make Rabbits: A Fable
- Let's Play
- Letters to Talk About
- Little Blue and Little Yellow (a New York Times Best Illustrated Children's Book of the Year, 1959)
- Matthew's Dream
- Mouse Days: A Book of Seasons
- Mr. McMouse
- Nicolas, Where Have You Been?
- Numbers to Talk About
- On My Beach There are Many Pebbles
- Parallel Botany
- Pulgada a Pulgada
- Six Crows: A Fable
- Swimmy (named by the National Education Association one of its "Teachers' Top 100 Books for Children" based on a 2007 online poll)
- Theodore and the Talking Mushroom
- Tico and the Golden Wings
- Tillie and the Wall
- Una Piedra Extraordinaria
- What?: Pictures to Talk About
- When?: Pictures to Talk About
- Where?: Pictures to Talk About
- Who?: Pictures to Talk About
- Words to Talk About
- "About Leo Lionni". Random House. Retrieved 11 March 2010.
- "Caldecott Medal & Honor Books, 1938-Present". American Library Association. Retrieved 11 March 2010.
- "Illustrator Comparison: Leo Lionni and Eric Carle". Retrieved 24 January 2012.
- National Education Association (2007). "Teachers' Top 100 Books for Children". Retrieved August 19, 2012.
- "New York Times Best Illustrated Children's Books of the Year, 1952-2002". The New York Times. 17 November 2002. Retrieved 21 May 2010.[dead link]
- Information from Random House
- Leo Lionni posters, hosted by the University of North Texas Libraries Digital Collections
- American Institute of Graphic Arts biography
- Art Directors Club biography, portrait and images of work
- Eric Carle Museum of Picture Book Art