Over the past thirty years, alloys based on the Bi2Te3 compounds (refrigeration) and Si1-xGex compounds (power generation) have been extensively studied and optimized for their use as thermoelectric materials. More specifically, applications range from small beverage coolers to power generation for deep-space probes such as those used in the Voyager and Cassini missions. However, despite extensive investigation of these traditional thermoelectric materials, there is still substantial room for improvement and entirely new classes of compounds will have to be investigated. This book, the fourth in a series from MRS, brings together experts in the field not to discuss further optimization of established materials, but instead, to discuss the development of the next generation of materials for small-scale refrigeration and power generation applications. Topics include: skutterudites; superlattice; new materials; quantum wires and dots; half-Heusler alloys and quasicrystals; TE theory; thermionics; devices, measurements and applications; clathrates and thin films TE.