There is a growing interest in island economies within Europe. In the European Union (EU) this has led to enhanced Cohesion Policy support for islands, along with a number of other regions facing geographical challenges. Because of major problems with data, comparative research on islands across different EU member states has been of limited extent. This paper explores the use of national data sets to undertake comparative cross-country analysis of islands. The paper concentrates on two member states, Greece and Britain, which have large numbers of offshore islands. Data from national population censuses are drawn upon to allow typologies of the islands to be developed. These typologies are utilised to identify similarities and differences between British and Greek islands.