Book excerpt: Symposium R, "Oxide Semiconductors" was held December 1-6 at the 2013 MRS Fall Meeting in Boston, Massachusetts. Oxide semiconductors are poised to take a more active role in modern electronics, particularly in the field of thin film transistors. While many advances have been made in terms of our understanding of fundamental optical and electronic characteristics, there remain many questions in terms of defects, doping, and optimal growth/synthesis conditions. This symposium proceedings volume represents recent advances in growth and characterization of a number of different oxide semiconductors, as well as device fabrication.