The coral reefs of the world, on which the news focus section of this issue of Science concentrates, are important for all sorts of reasons. For many, exploration by diving provides a unique connection with a fascinating natural ecosystem. For scientists, including climate scientists, the health of reefs provides insight into the physical and biological welfare of the oceans as a whole. And for conservation biologists, shallow-water reefs are remarkable hot spots of biodiversity; those that surround oceanic islands often include a level of specialized endemic species that rivals that on the islands themselves. But the corals of the world are in trouble, and that9s why we need the International Year of the Reef (IYOR) in 2008.