New electronic materials have the potential to enable wearable computers, personal health monitors, wall-scale displays and other systems that are not easily achieved with established wafer based technologies. A traditional focus of this field is on the development of materials for circuits that can be formed on bendable substrates, such as sheets of plastic or steel foil. More recent efforts seek to achieve similar systems on fully elastic substrates for electronics that can be stretched, compressed, twisted and deformed in ways that are much more extreme than simple bending. This article highlights some recent progress in this area, with an emphasis on materials approaches and demonstrated devices.