The late medieval monetary history of Brunswick-Lüneburg is presented in three edited account books. The monetary history and coinage policy of the Dukes of Brunswick-Lüneburg, as well as the cities of the duchy, are comprehensively covered from the founding of the duchy in 1235 to the transition to large silver coinage in 1501/1502. The first part of this two-volume work provides an edition of three Brunswick account books, thus forming the basis for the investigations conducted in the second part.