Critical Realist Activity Theory provides an exciting new contribution to the New Studies in Critical Realism and Education series by showing how the nature of learning is tantamount to the critical realist notion of the dialectic. The science of learning is too important to leave solely to the sciences; it needs philosophy as well. The task of this book is to take a further step and clear the conceptual field for an ontologically grounded view of the science of learning through critical realism, making use of dialectical critical realism and the philosophy of meta-Reality, as well as basic critical realism. The objective of the book is neither to accommodate the nature of learning to strategies and techniques, nor to adjust to the demands of institutions and authorities. Its key goal is to explain how the very nature of learning constitutes itself; that is, its aim is to explain how a stratum of learning emerges out of the need to absent something that has been left out in human reality. In this precise sense, the book does much more than simply reveal the aspects of reality that have been omitted from the conceptualization of learning, it helps to reformulate a proper understanding of the nature of learning. An implication of this understanding of learning is that it begins to advance the fundamental question of what it means to be a human being. This book will be of great interest to academics and students interested in Vygotsky, Luria, Activity Theory and Critical Realism more generally across both Europe and the US.