The thesis examines Marten van Cleve’s painting the Massacre of the Innocents from the Stockholm University Art Collection through a series of technical examinations that were conducted at Spökslottet in January 2020 (X-ray, UV, IRR). The aim of the thesis is to examine Marten van Cleve’s painting technique, style and composition by comparing the painting with five contemporary similar versions of the subject the Massacre of the Innocents. Moreover, the thesis compares the underdrawing of the painting from the Stockholm University Art collection with the drawing from the Göttingen University art collection that are similar in composition and signed by Marten van Cleve. Additionally, the thesis examines the relationship between preparatory drawings and underdrawings in the artists environment in order to learn more about Marten van Cleve’s painting process as well as gain insight into the practice of contemporary 16th-century Flemish artists.