Based upon 6 years research of primary sources, this study examines this medieval forest in more detail than previously. It covers the adaptation of a Royal hunting forest to an industrial and commercial enterprise; life in the forest for the people who lived there; peoples' common rights; forest administration; the history of the landscape; what may be seen today. Duffield Frith covered a large area either side of the River Derwent around Duffield and Belper, north of Derby, stretching from near to Ashbourne to Ripley.