In 1998, at the outset of the present doctoral study, Pieter Brueghel the Younger’s oeuvre had never been researched in any depth from a technical point of view. The thesis provides a new assessment of many of the outstanding issues linked to Brueghel’s workshop, based on a study of the techniques and materials on a wide sample of paintings. In combination with the classic approach of comparing images, new technical evidence was exploited to reconsider such themes as the question of the original models, the issue of variants amongst copies of the same composition, workshop practice, collaboration within the studio and the copy process itself. There is also a personal assessment of more subjective matters, such as the identification of the hand of the master and the case for Brueghel’s creativity.