Symposium B, 'Thermoelectric Materials Research and Device Development for Power Conversion and Refrigeration', held from November 26-30 at the 2012 MRS Fall Meeting in Boston, Massachusetts, was the tenth in a series of symposia on state-of-the-art materials and technologies for direct thermal-to-electric energy conversion that produced proceedings with primary focus on material and technological advances of thermoelectrics and thermionics (see MRS Proceedings volumes 234, 478, 545, 626, 691, 793, 886, 1044 and 1166). In this symposium there were 263 contributed presentations, the largest by far at the MRS, including 10 invited talks and 168 poster presentations. These presentations were given from researchers from academia, national laboratories, and industry in the United States, Asia and Europe. The symposia covered a broad range of topics in the areas of materials, measurement techniques, and device development. This volume provides an overview of the exciting recent developments in the field.