This book is a study of the L1 attrition of German among German Jews who emigrated to anglophone countries under the Nazi regime. It places the study of language attrition within the historical and sociocultural framework of Weimar and Nazi Germany, applying issues of identity and identification to first language loss and maintenance. Morphosyntactic features of German are looked at in free spoken discourse, in an analysis of both ‘interferences’ or ‘errors’ and their overall (correct) use. The picture of L1 proficiency which emerges from these investigations is then related to a taxonomy of intensity of persecution, clearly demonstrating this to be the decisive factor in language attrition, while showing other factors such as age at emigration and intermediate use to be inconclusive.