Synopsis The present monograph includes a detailed account of the archaeological excavations carried out by the authors at the stone age settlement of Paisra, district Munger, Bihar, between 1980 and 1988. Paisra is a unique stone age settlement of the Indian sub-continent in more than one respect. First, the site has preserved unmistakable evidence for habitational floors of the acheulians, covering an area of several hundred square metres. Second, associated with the floors were found not only a large number of finished and semi-finished implements, flakes, cores and debitage, but also various hammers, anvils, lumps of raw material and other rock pieces. Third, the excavations have also revealed such remains as several post-holes and stone alignments of acheulian settlers, which can be logically interpreted as indicating the existence of more than one type of structures. Lastly, Paisra had also been a camp-site of mesolithic settlers in sixth millennium B.C. Incidentally, it remains the only mesolithic settlement of the entire eastern India, which has a radio-carbon date.