Book excerpt: Solid-state electrochemical devices, such as batteries, fuel cells, membranes, and sensors, are critical components of technologically advanced societies in the 21st Century and beyond. The development of these devices involves common research themes such as ion transport, interfacial phenomena, and device design and performance, regardless of the class of materials or whether the solid state is amorphous or crystalline. The intent of this international symposia series is to provide a forum for recent advances in solid-state ion conducting materials and the design, fabrication, and performance of devices that utilize them. The papers in this issue of ECS Transactions were presented at the 6th Solid State Ionic Devices symposium, at the 214th meeting of The Electrochemical Society, October 12-17, 2008 in Honolulu, Hawaii.