Sponsored by the Technical Council on Lifeline Earthquake Engineering of ASCE. On September 30, 2009, an earthquake with a moment magnitude of 7.6 occurred off the west coast of Sumatra in Indonesia, followed 22 minutes later by an aftershock with a magnitude of 6.2. The epicenter was located about 50 kilometers southwest of Padang, a city in the province of West Sumatra with a population of 900,000. The earthquake and aftershock caused extensive damage in Padang and 85 percent of residential buildings were declared unsafe for occupancy. The area also experienced significant damage to lifelines, especially water supply, electric power, and telecommunication service. This TCLEE report discusses in detail the effects of the earthquake, as observed by an ASCE-TCLEE investigative team of civil engineers in late October 2009. The team examined the performance of lifeline infrastructure systems, including bridges and roads, electricity, water, telecommunications, the seaport, and the airport. An overview of each system's performance is provided, followed by descriptions of damage to specific sectors or locations. The effectiveness of Indonesia's programs for emergency preparedness is described and the performance evaluated. The final chapter provides the results of an assessment conducted one year later regarding improvements to preparedness and progress in recovery. This monograph will be of particular interest to civil engineers, managers, planners, emergency management personnel, and government officials charged with maintaining lifeline infrastructure systems to withstand earthquakes and other natural hazards.