Growth of lava domes is common at many volcanos, especially those around the Pacific rim, and the pyroclastic flows associated with these domes constitute one of the most serious of all volcanic hazards. Over thirty-five scientists from Japanese and U.S. universities and government agencies gathered in Palo Alto, Calif., from March 8–12, to discuss and plan new joint research aimed at improving our understanding of collapsing volcanic domes and the destructive pyroclastic flows and surges they generate. This workshop was the first of several to be held in accordance with the Panel for Volcanic Disaster Prevention under the Japan-United States Science and Technology (JUST) Agreement of 1988 and was part of both countries' response to the International Decade for Natural Disaster Reduction (IDNDR).