Scalable elements that can be switched between widely-separated non-volatile resistance states at very low power are desirable for applications in next generation memory and logic. One promising approach involves the use of solid ion-conducting films. A mobile metal ion-containing glassy electrolyte film sandwiched between an oxidizable metal layer and an inert electrode constitutes a device which reversibly transitions between high and low resistance states. The resistance reduction occurs by the formation of a nanoscale conducting pathway created by reduction of the metal ions. A reverse bias dissolves the connection. In addition to possessing the speed, endurance, retention, and CMOS compatibility required of future switching elements, such devices have excellent scaling prospects due to their low operational energy and demonstrated physical scalability. This paper discusses the materials and mechanisms of ionic memory and presents the electrical characteristics of devices formed from Ag-Ge-S and Cu-Si-O electrolytes as examples of the technology.