THERE ARE SEVERAL actors involved in the debate about the regulation of nanotechnologies. These include: international organisations; national, regional or municipal governments; corporations and enterprises; nongovernmental organisations (NGOs); trade unions and others. As a result of this, we can fi nd a wide array of proposals that go from the de facto moratorium (related to the commercialisation of nanoparticles and nanostructures as long as there is no reliable information about their threat to health and the environment) to the argument that the lack of regulation, in fact, facilitates the rapid development of these novel and powerful technologies. At the same time, we can fi nd proposals suggesting the adoption of voluntary regulations, mandatory regulations applied to specifi c products and many other possibilities. Each one of these actors provides arguments to justify their proposals, but often their reasons are not explicit; moreover, often they are hidden under general principles such as safety and environmental concerns, thus complicating the understanding of the foundation of their views.