This collection of forty-nine letters, edited in full here for the first time, are addressed to Sir John Bellenden of Auchnoull (1520δ-1576) or members of his circle and offer a precious window onto the turbulent and often obscure history of Orkney and Shetland in the sixteenth century as the Northern Isles were subject to increasing intervention from the Scottish mainland. Anderson and Ballantyne provide an extensive contextual introduction and annotate the letters themselves as well as providing a glossary of the more obscure Middle Scots words used. This edition will join previous works by these two authors, including Anderson's monographs on the Stewart earls of Orkney and Ballantyne's Shetland Documents, as an indispensable resource for the early modern history of the Northern Isles.