Head pose and eye gaze estimation is a hot research topic in computer vision as it is deeply related to someone’s intentions and attention. Despite many years of research, it remains a very difficult and largely unsolved problem in unconstrained environments. There have been several books on face recognition in which the head pose and eye gaze are only discussed independently. This book is the first to provide a comprehensive introduction to the head pose, eye gaze and their integration from a computational and implementation perspective. Face detection, a related topic, is also discussed. This book has been written with an emphasis on face domain knowledge that can provide fast and robust solutions to estimate the head pose and eye gaze. Domain knowledge is not about features but more anatomical properties. This book will serve as a reference for students, researchers in the field of face recognition and also practitioners in the field of face-based commercial applications including engagement, disability assistance and HCI. The content in this book does not require particular knowledge. Nevertheless, some basic knowledge of geometric computation would be useful for the reader.