This is the first of two volumes, which together form a catalogue of abbots and priors, abbesses and prioresses, of English and Welsh monastic houses between 940 and 1377. This present volume covers the period to 1216, and provides invaluable material for specialists in the period to study the biographies and personalities of the monastic orders, and to date undated documents. First published in 1972, it won international acclaim as a fundamental tool of medieval research. It is now reissued with substantial additions and corrections by Professor C.N.L. Brooke.