Chicka Chicka Boom Boom is a bestselling American children’s book written by Bill Martin, Jr. and John Archambault, illustrated by Lois Ehlert,[1] and published by Simon & Schuster in 1989. The book features anthropomorphized letters. The book charted on The New York Times Best Seller list for children’s books in 2000. The lowercase letters climb up the coconut tree in alphabetical order, until their weight causes the tree to lean and all the letters fall out of the tree. Capital letters (the older relatives of the lowercase letters) come to rescue them.