This article addresses conversion and its consequences for a Bactrian family known as the Mir family during the Umayyad and early Abbasid periods. It explains the social, legal, and economic ties that bound this Bactrian family, and the problems created within the family after a member of it converted to Islam. Based on a systematic analysis of a group of Bactrian and Arabic documents issued for the members of this family by the local Bactrian and Muslim authorities, this article will show the centrality of the ‘household’ in the Bactrian society and the changes that occurred in it after the arrival of Islam. It argues that conversion to Islam seriously affected this family and eventually dismantled it. Although conversion did not remove the kinship within the household, it ended cohabitation and joint ownership, which were central social elements in the Bactrian law that kept the household together.