Scholars have traditionally focused on the subjects and meanings of Hieronymus Bosch’s works, whereas issues of painting technique, workshop participation, and condition of extant pictures have received considerably less attention. Since 2010, the Bosch Research and Conservation Project has been studying these works using modern methods. The team has documented Bosch’s extant paintings with infrared reflectography and ultra high-resolution digital macro photography, both in infrared and visible light. Together with microscopic study of the paintings, this has enabled the team to write extensive and critical research reports describing the techniques and condition of the works, published in this extraordinary volume for the first time.