This thesis focuses on conflict within families in Normandy, c. 1025 to 1135. Despite the occurrence of several acute struggles within the ducal house during this period, and a number of lesser known but significant disputes within aristocratic families, this topic has attracted little attention from historians. Kin conflict was cast by medieval commentators as a paradox, and indeed, it is often still regarded in these terms today: the family was a bastion of solidarity, and its members the very individuals to whom one turned for support in the face of an external threat, so for a family group to turn against itself was aberrant and abhorrent. In this thesis, I draw on significant narrative and documentary evidence to consider the practice and perception of family discord. When considered in its broader setting, it emerges that kin disputes were an expected and accepted part of Norman society at this time. I begin by introducing the topic, justifying my approach, considering the relevant historiography, and providing an overview of the sources. In chapter one, I examine the representations of family and conflict in a range of primary sources to glean contemporary views. In chapters two and three, I focus on the practice of conflict within the ducal family, considering the causes of disputes, and then the place of internal ducal dissension in the Norman world. Chapter four analyses the same issues in relation to discord within aristocratic families, before chapter five explores family disputes which arose from patronage of the Church. In the conclusion, I consider the Norman example within its comparative contemporary milieu and ponder the broader themes of family conflict.