To enable children to develop towards becoming part of the solution to environmental problems, it is essential that they are given the opportunity to become familiar with the natural world from early childhood. Familiarity is required to develop understanding of, care for and, ultimately, action in terms of protecting the natural world. As adult-led reading of picture books is a common form of indirect exposure to the natural world for young children, this study examines the biological accuracy of the representation of whales and dolphins in the images and text of picture books. Of the total of 116 books examined, 74 (63.8%) had errors in the representation of cetaceans in the images and/or text. Errors were identified in both fictional (mean = 8.0 errors/book, SD = 11.1, n = 55) and non-fictional (mean = 2.3 errors/book, SD = 4.9, n = 61) books. The potential impact of the errors is discussed, and suggestions are made as to how the impact could be reduced and how the biological accuracy of picture books could be improved.