Greetings, and welcome to the ROC Centennial Workshop on THz Science and Technology (THz Workshop 2011), held in Hsinchu, Taiwan on Dec. 12th, 2011.     Our intention, and that of the sponsoring organizations, is to provide a venue where attendees can explore the latest cutting-edge research and applications of THz science and technology.. The workshop was also held in celebration of the 100th anniversary both of the Republic of China and Tsing Hua University. This year, THz workshop 2011 covers a broad range of topics, e.g., high-power THz radiation sources, THz spectroscopy and sensing, THz metamaterials and .THz wireless communications. We are very pleased and indeed honored to have distinguished guests from Fukui University’s renowned Research Center for Development of Far-Infrared Region as invited speakers. They will be joined by our local scholars, who will contribute many invited talks and poster presentations in the technical program.     THz workshop 2011 is most grateful to all of our sponsors, the Frontier Research Center and Applied Sciences of Matters, Office of Research and Development in NTHU and Physics Research Promotion Center, NSC, who graciously provide the much needed financial support to stage this event. Your participation is of course most essential in making THz workshop 2011 a great success and at the same time showcasing the strength, dynamics and the diversity of Taiwan's academic and industrial communities in THz research and technology development.     As Conference Chair, I cordially invite all of you to participate and enjoy the excitement and fun of THz workshop in Hsinchu. 　 Ci-Ling Pan 潘犀靈 Conference Chair, THz Workshop 2011 Professor and Chair, Dept. of Physics National Tsing Hua University Hsinchu, Taiwan Republic of China