This volume is based on papers presented at "The Norway/United Nations (UN) Conference on Alien Species" which was hosted by the Norwegian Ministry of the Environment in collaboration with the United Nations Environment Programme (UNEP), the Secretariat of the Convention on Biological Diversity, the United Nations Educational, Scientific and Cultural Organisation (UNESCO), the International Conservation Union (lDCN) and the Scientific Committee on Problems of the Environment (SCOPE) of the International Council of Scientific Unions (ICSU). The organisation and sponsoring of the conference was also a joint venture between the Norwegian Ministry of Environment, the Ministry of Agriculture, the Ministry of Fisheries and the Ministry of Foreign Affairs. The Conference was held at Royal Garden Hotel, Trondheim, Norway, 1-5 July 1996. This was the second Trondheim Conference on Biodiversity, the first being the NorwaylUNEP Expert Conference on Biodiversity, 24-28 May 1993. The conference was organised by the Norwegian Directorate of Nature Management, the Norwegian Institute for Nature Research (NINA) and the Norwegian University for Science and Technology (NTNU) and its Centre for Environment and Development (SMU), all based in Trondheim. These institutions are all active in the fields of management, education and research related to biological diversity. Weare extremely grateful for the support we have received from all these national and international institutions.