This unique text distils the latest thinking in various academic fields and its relevance to all equestrian sports and activities, highlighting best practice that logically emerges from a full understanding of the inner workings of horses. In precisely the same way that a car mechanic's knowledge of vehicle performance can only be improved by an education in mechanical engineering, the efficiency of horse training can only emerge from deeper knowledge of the horse's ethology, physiology, mental capacities, learning processes and biomechanics. Training systems that align with such evidence-based knowledge ultimately result in optimal equine welfare as well as safety for humans, not only because of gains in efficiency but also because they reveal the actual hard-wired needs of the horse in contrast with the human-centred narratives that have pervaded and polluted equestrian education for many millennia. This text represents another leap forward from Andrew McLean's earlier works that began with Horse Training Mclean Way (2002), The Truth About Horses (2004) and then Academic Horse Training (2008). As a result of the burgeoning scientific revelations in Equitation science over the last decade or so, the time is ripe to put it all together in a practical text. This practical text consists of four volumes: first principles, in-hand training, under-saddle training, and addressing challenges. These volumes align with the peer-reviewed academic text Equitation Science (of which Andrew McLean is also co-author). The intention of this volume is to simplify the scientific language of Equitation Science and show how it can be incorporated into everyday interactions with horses in husbandry, and all aspects of horsemanship.