The Encyclopedia of the Sciences of Learning is the first major reference work in the growing and highly visible field of learning sciences. It brings together definitional entries from scholars who represent the breath of this interdisciplinary area of study, teaching, and practice: biology, neuroscience, psychology, computer and information science, philosophy, anthropology, sociology, education, and a range of narrower technical and applied fields. Given the increasing amount of scholarly and popular attention to the dimensions and questions of human learning, it’s important to note that this encyclopedia devotes equal time to animal and machine learning as well; this is a significant difference that sets it apart from previously-published reference works on educational psychology. It also maintains an international sensibility in terms of contributors and topics and aims for an objective tone overall. Where it addresses specific institutions, politics and cultures of learning, it does so primarily to contextualize a specific learning behavior, process, method, theory, or concept.