While there has been much interest in this topic, no generally accepted definition of dual use has been forthcoming. As a contribution to this issue, it is maintained that three related kinds of things comprise the category of dual use: research, technologies and artefacts. In regard to all three kinds, difficulties are identified in making clear distinctions between those that are and are not dual use. It is suggested that our classification should take account of actual capacities and willingness to (...) make use of these objects for ‘bad ends’ and not the mere possibility that this could be done, and here three ‘contextual factors’ are identified. A (provisional) definition is proposed that takes account of threats and risks. (shrink)