This National Academies Press publication summarizes the proceedings of a workshop that explored issues associated with two manuscripts reporting work on mammalian transmissibility of a lethal H5N1 avian influenza strain and dual use research of concern in general. The workshop was convened by the National Research Council's Committee on Science, Technology and Law, in conjunction with the Board on Life Sciences and the Institute of Medicine's Forum on Microbial Threats on May 1, 2012.