Increasing awareness and concern for energy resources and the environment have stimulated significant advances in materials and technology for energy conversion in recent years. This volume, the ninth in a popular series, focuses on novel materials, materials processing and device technologies for direct thermal-to-electric energy conversion, and emphasizes the interdisciplinary nature of research needed to advance the field. The volume begins with an overview of the state of the art in high-temperature thermoelectric materials by Harald Boettner. The section on nanocomposite materials includes an overview on bulk nanostructured materials, one of the most highly investigated areas in the thermoelectric community, by Mildred Dresselhaus. A third overview article, by Peter Rogl, addresses the potential of inverse clathrates for thermoelectric applications. Additional topics include: applications and devices; nanocomposite and nanostructured materials; theoretical investigations; bulk materials and oxide materials.