Island biodiversity is under serious threat from human activities. To understand how species adapt or go extinct as island environments change, integrating biology and geology is crucial. By bringing biologists and geologists working on various island systems and taxonomic groups worldwide, the overarching aim of this Lorentz Center workshop is to develop a common working framework that bridges the divide between biological and geological research performed on islands in order to better understand, protect, and predict biodiversity on islands in the face of global change and global challenges. A key practical objective will be to develop a framework to harmonise biological and geological datasets and models (across the two disciplines, but also across temporal and spatial scales) so that both fields can make progress in addressing questions about biodiversity on islands and to improve biodiversity forecasts on islands under threat.