Coral reefs are the only ecosystem that is strongly defined by a geological component - most definitions require that the biological community produces its own build-up of calcium carbonate. In terms of "reef-building," the geological record reveals that coral reefs have flourished over the past few million years, particularly during interglacial periods. Based on our observations of modern-day reefs, which are limited to the past few centuries, we tend to link "coral reef health" to carbonate production; however, reef ecosystems face future global-scale environmental changes that may decrease their reef-building capacity. In contrast to past discussions of the factors which determine reef-building potential by a coral reef community, the essential question that arises from this review is: How important is reef building to a coral reef community?