This volume provides the first comprehensive account of the geology of Sumatra since the masterly synthesis of van Bemmelen (1949). Following the establishment of the Geological Survey of Indonesia, after WW II, the whole island has been mapped geologically at the reconnaissance level, with the collaboration of the geological surveys of the United States and the United Kingdom. The mapping programme, completed in the mid-1990s, together with supplementary data obtained by academic institutions and petroleum and mineral exploration companies, has resulted in a vast increase in geological information, which is summarized in this volume. The synthesis of structural controls on sedimentation and magmatism during the tectonic evolution of Sumatra since the late Palaeozoic has provided a background for the formation of economic deposits of metallic minerals, coal, oil and gas. The volume provides a sound basis for future geological research and for the exploration of the energy and mineral resources of the island.