Tourism is the main industry in many islands around the world. Islands connect with each other and with mainland markets in a complex system of relations of competition and cooperation (coopetition). This article analyses islands’ cooperation strategies through the management of brand architecture and how visits to one island can influence visits to others. This paper aims to provide island destination management organisations with information on how islands can effectively design their brand architecture-inside and outside their own archipelagos-depending on mainland markets. The study includes in its analysis some of the main tourist islands and archipelagos in the world (particularly the Canary Islands but also Cyprus, Malta, Balearic Islands, Maldives, Caribbean, Azores, Madeira, Cape Verde, and Greek islands), with a sample of 6,964 tourists from the main worldwide tourism market, Europe, and an analysis of 16 European markets.