The authors in this book treat a number of issues that pertain to relations between ontogeny, phylogeny, and historical development. Some show parallels among them, others show convergences, while still others show how they can inform each other. Chapters deal with the importance of this area for developmental theories, the distinction between changes in expert knowledge (as it pertains to historical development) and novice knowledge (ontogenesis), what constitutes a theory in science and in children's thought organizations, and the importance of historical models for characterizing children's conceptual structures.