The aim of this paper is to contribute to the question of Jewish identity in the Second Temple Period through the perspective of the conversion of the royal dynasty from Adiabene. In this context, several conclusions are suggested. First, the main ancient account about the conversion of the Adiabenean royalty (“the Adiabene Narrative”: A.J. 20:17-96) perfectly fits the model of ethnicity (D. Boyarin, S. Mason). Although the model of dual (multiple/nested) ethnicity trips over the “breaking motif ” of the Adiabene Narrative, it remains a very plausible option, especially in the light of other sources that show how the Adiabenean kings continued to properly function in the Parthian kingdom. Finally, the available sources do not contain direct evidence to support the model of conversion as a purely religious process.