This book is a philosophical analysis of knowledge in practices, focused on knowing how, tacit knowledge and expert knowledge. Knowing in action is the key concept. It covers understanding, well-functioning routines as well as successful learning processes. It is argued that knowledge-in-action is more basic than propositional or theoretical knowledge. Key notions are knowing as a kind of attentiveness or a way of being in the world, knowing as continued learning, and knowledge as what leads people in the best way. The book is a contribution to the contemporary philosophical discussions about knowing how, tacit knowledge and expert knowledge. At the same time, it is written as an interdisciplinary and case-based introduction to the epistemology of knowing and learning.