INTERRAD XII  (12th Meeting of the International Association of Radiolarian Paleontologists) was held from September 14 to 17, 2009 in the newly built "Nanjing Museum of Palaeontology" at Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, and the campus of the Southeast University, within walking distance from downtown Nanjing. A series of scientific sessions including plenary and special sessions, and special group meetings, in addition to pre-, post-conference and mid-conference field excursions were organized.