After the publication of Volume III the approach of the first three volumes needed to be revised. It had become clear that the strictly chronological method employed in those books would not be effective for the final period, covering 1642 until 1669 (the year that Rembrandt died). The project group therefore chose for a method in which larger groups of pictorially interconnected works were studied, such as the self-portraits, portraits, historical paintings etc. Rembrandt's workshop practice was scrutinised more closely as well. In Volume IV the focus lies on Rembrandt's self-portraits. During this research it became obvious that matters of authenticity cannot be viewed separately from questions relating to the original function and meaning of these works. Rembrandt's intriguing life-long practice of portraying himself in front of a mirror is examined in depth in this volume. As a result, not only has the group of approximately forty painted self- portraits gained transparency, but also new insights have been developed regarding Rembrandt's drawn and etched self-portraits. The problems of authenticity relating to a substantial amount of self- portraits which in the past were attributed to Rembrandt in this volume receive an unexpected nuance: through a combination of technical and stylistic research it is demonstrated that some of Rembrandt's self- portraits were in fact painted by others in his workshop. In clear and accessible explanatory texts the different paintings are discussed. Among the many illustrations are life-size colour reproductions of the faces of the self-portraits under discussion. Details are shown where possible, as well as the results of modern day technical imaging like X-radiography. The volume contains an # in several respects eye-opening # essay by the head of the Rembrandt Research Project, Ernst van de Wetering, on the problems of authenticity and function of Rembrandt#s self-portraits. In addition, the book includes groundbreaking contri