This chapter presents a number of excellent summaries of the Mesolithic period which cover the details of the range of sites found in both Britain and Ireland. It aims to paint a picture of life just before the start of the Neolithic and since the Mesolithic period was thousands of years long, it would not be very insightful to discuss the archaeology of sites that were occupied 5,000 years before the Neolithic began. The chapter explores what we do know about the lives of people who were living in the late Mesolithic of Britain and Ireland. It considers one of the best-known sets of sites from this period, the middens on Oronsay, Argyll and Bute, before expanding the discussion out to consider various aspects of life in the late Mesolithic. The tiny island of Oronsay is found to the south of Colonsay, itself a small island which is part of the Inner Hebrides in western Scotland.