This study concerns itself with the 'monochrome' mural paintings of the Middle and Late Imperial Age in Italy. The paintings are to be found in bedrooms, corridors and domestic offices, but also in the more humble living quarters of the poorer classes in society. What are known as 'ancillary room decorations' have not hitherto been regarded as a decorative genre in their own right. The study shows, however, that they also go through a process of stylistic development independently of the style of the principal rooms, and that a chronological assessment of them is possible. The mural paintings, most of them previously unpublished, come mainly from Rome and Ostia and are presented in a catalogue. They also allow conclusions to be drawn about the history of domestic living from the Hadrianic to the post-Severian period.