Accidents involving radioactive sources and reports of illicit trafficking in radioactive materials have raised awareness of the safety and security risks created by sources that are outside effective control, and the attacks of 11 September 2001 have triggered international concern about the potential malevolent use of radioactive sources by terrorist groups. The International Conference on Security of Radioactive Sources was organized with the aims of promoting information exchange on, and raising awareness of, key issues relating to the security of high risk radioactive sources, and of fostering a better understanding of the measures necessary to improve the security of such sources and to enhance preparedness for radiological emergencies. These proceedings contain the addresses and papers presented at the conference, as well as records of the discussions and the conference findings.