"Whistle for Willie" is a children's book written and illustrated by Ezra Jack Keats. The story follows a young boy named Peter who wants to call his dog, Willie, by whistling. However, Peter struggles to make the right sound, leading him to explore different ways to practice his whistling. As Peter plays in his neighborhood, he observes the vibrant city life around him, filled with various characters and activities. Eventually, he discovers that with persistence and creativity, he can successfully whistle for Willie, showcasing themes of determination and the joy of childhood exploration.