Although our popular culture stereotypes relationships with in-laws as problematic, these relationships have largely been overlooked by communication researchers. In contrast to existing studies focusing on dyadic relationships, this study looked at how in-laws are assimilated into the family group as newcomers, using structuration theory to examine how routines are reproduced in families. In personal interviews, participants described how their families had assimilated newcomers or how they themselves were received into their spouse's families. A thematic analysis revealed specific communication routines that had to be adjusted upon entry of newcomers, including conversational topics, expected amount of interaction, use of joking, and conversational styles. Adjustments to these routines, although difficult to negotiate because they were not openly discussed, helped to transform the family of childhood into the family of adulthood. Structuration theory would suggest that the perceived stress in relationships with in-laws occurs because newcomers upset the comfort of families by disrupting their communication routines.Keywords: Structuration Theory; In-Laws; Assimilation; Socialization; Family Families have routines that they have produced and reproduced throughout the course of their life together. According to structuration theory (Giddens, 1984), these routines create a sense of ontological security*a sense that all is right with the world, that this is how a family should conduct its daily life. When a family member introduces a new spouse into the family, routines are inevitably impacted. The negative stereotypes of in-laws presented in our popular culture, in part, construct our low expectations for relationships with in-laws. However, what may be problematic is not that in-laws themselves are problematic, but that families live within their own routines and expect the newcomer to adjust to the family's routines,