The investigation is focusing on why island autonomy occurs. Our point of departure considers three European autonomous islands: the Azores, the Faeroe Islands and the Isle of Man. Since the nation-building process has had a long tradition in Europe, we claim that the circumstances have been prosperous for islands achieving special status within their metropolitan countries. Further we assume that different legal traditions lead to different kinds of autonomy arrangements. The selection has therefore been to include different legal aspects as the Nordic dimension with the Faeroe Islands, the South European tradition (which is a mixture of various other traditions) represented by the Azores, and the British tradition with no written constitution with Isle of Man as our prime example. The analysis is performed using QCA, MVQCA and Fuzzy Set.