The starting point of this work is an observed tension in recent scholarly discussion of the ethical content of Ephesians 4.17-6.9. On the one hand, Ephesians 4.17-5.21 has been interpreted as drawing a social or ethical contrast between the addressees and the outside world, and even as encouraging or legitimating social withdrawal or separation from outsiders. On the other hand, the household code in Ephesians 5.21-6.9 has been read as encouraging integration into the wider society in an attempt to curb accusations of social disruptiveness. These social goals seem to be at odds, but rarely is this reflected on or addressed in scholarship. Upon a close and detailed study that utilizes traditional exegetical methods, comparative analysis and social identity theory, this thesis argues that Ephesians 4.17-6.9 exhibits a consistent strategy of promoting group distinctiveness while utilizing Greco-Roman ethical values and traditions to promote internal cohesion among the readers. In Ephesians 4.17-5.21, the author uses a rhetoric of differentiation to distinguish his readers from outsiders yet the ethics he espouses are commonly held traditions and moral values. The household code in Ephesians 5.21-6.9, which is grammatically and conceptually linked to the preceding ethical instruction (4.17-5.21), transforms conventional household morality into group-specific ethics to enhance mutuality among the readers in their households. Thus, the readers are encouraged neither to separate from society nor to integrate further into it, but to live and function within society as members of the 'household of God' in one accord.