What did medieval people call the animals they lived and worked with? Why did they give them the names they did? This book sets out to answer these questions. Drawing evidence from literary, documentary and material sources, it surveys the surviving evidence of pet-naming from the period, as well as examining the labels given to livestock and working animals, and the folk-names given to wild birds and beasts. Alongside building up a corpus of names, the conventions that directed animal naming in the Middle Ages are considered, as well as how proper nouns behaved when given to non-human organisms. Through its inquiry, the book lays bare the periods larger attitudes towards animals, their functions and identities, and at the same time sheds light on how the Middle Ages conceived the natural world as a whole and its relationship with human beings and their culture.