From sunup to sundown, winter through fall, Leo Lionni's signature illustration style and a toddler-friendly text ask a simple question: "When" is time of day/season? One of four board books that celebrates the art and imagination of Leo Lionni, this book is a perfect introduction to the concepts of time and seasons for busy toddlers, as well as a wonderful stepping stone into the world of one of our best-loved children's book creators.