This book argues that despite its month-long existence in the geopolitically volatile and amids the First World War, the Transcaucasian Democratic Federative Republic (TDFR), with its federative nature and the various discussions about federalism and federation that it provoked, continued to have an appeal for Georgians, Azerbaijanis and Armenians as well as the Great Powers well beyond its dissolution. Moreover, the experience of TDFR reifies federalism as a key concept in the modern history of the Caucasus.