The authors of the essays collected here explore the ways in which late antique groups defined their own socio-political borders and created secure in-group identities by means of discourses on heresy and heretics. A wider definition of heresy and heretics as real or constructed internal opposition and internal enemies leads to a new understanding of ancient sources as well as to new comparative possibilities. Some of the contributing authors look at the social setting of heresiology, and examine how it served to regulate interaction between communities. Others consider the different functions of heresy-making discourse as a simultaneous process of describing and disqualifying groups of perceived dissenters. Combining presentations from various fields, the authors reconsider the phenomenon of 'heresy' in late antiquity in the broadest possible scope. They focus on examples of the ways in which late antique groups defined themselves as righteous, in the process of describing imagined communities as vicious. They analyze cases in which authors or groups sought to present dangerous encounters by describing the other in highly conventionalized terms established through heresiological traditions and the creation of cliches and stock characters. The authors also examine cases in which heresy-making discourses effectively push with the left and bring in with the right, as the Babylonian Talmud has it, inasmuch as the proclamation of a radical divorce from 'heretics' allowed for the domestication of their ideas and practices.