Medieval painting was a craft. The anonymous Montpellier Liber diversarum arcium ('Book of various arts') is a handbook prescribing how that craft was to be practiced. It contains over five hundred art-technological instructions or 'recipes' in Latin. Unlike the vast majority of medieval artists' recipe books, this content is highly structured and organised, such as to form a complete handbook or course on painting. This Liber diversarum arcium is probably the most substantial and comprehensive medieval painters' technical recipe book to survive. It summarises the state-of-the art in the European workshops of the fourteenth century. This volume makes the Liber diversarum arcium usable to modern readers for the first time, by restoring the text in over 150 places where its corruption obscures the technical sense, by translating the text into English, and by providing a running commentary to explain the technical processes and technical terminology.