The attribution of portraits, landscapes, history painting, and genre scenes to Rembrandt over the years is discussed. Compounding the problem of misattribution is the existence of numerous imitations and forgeries. In 1968 a group of seven Amsterdam-based art historians convened to launch the Rembrandt Research Project and assume the responsibility for producing a catalogue raisonné. With funding from the Dutch government the members of the project set out to examine physically and analyze scientifically every painting Abraham Bredius has attributed to Rembrandt in the 1930's and a few more recent discoveries. A questionnaire was developed to cover technical examination and the existence of x-radiographs, infrared or ultraviolet photographs, dendrochronological investigation, etc. Dossiers were compiled on more than 600 paintings. Some details of the young Rembrandt's working methods are discussed in the article. -- AATA