This chapter examines young children’s picture books, both print and electronic, that focus either explicitly or implicitly on mathematical concepts and methods. A focus on math picture books is valuable because they can serve as a friendly and meaningful introduction to math for both child and adult. Our perspective derives in good measure from developmental psychology and cognitive science, because we believe that science-based ideas about children’s thinking and development can contribute to the understanding and betterment of children’s literature and its uses. At the same time, we are sensitive to a humanistic perspective that values picture books as literature. The chapter examines the effectiveness of picture books in promoting children’s learning of math concepts and methods, as well as their acquisition of relevant math vocabulary. To help adults select high-quality picture books, we present an analysis of generally (there are always exceptions!) desirable and undesirable picture book features. The analysis focuses on literary merit as well as on special features that are essential for conveying mathematical ideas. The chapter concludes with a discussion of practices that can promote sensitive math picture book reading, a suggestion about writing math picture books, and a description of future directions for research.