Nanotechnologies refer to “technologies of the tiny”. They span domains as diverse as computing, material science, medicine, energy production and storage, etc., bring together fields as varied as physics, chemistry, genetics, information and communication technologies, and cognitive sciences, and should become virtually ubiquitous before long. Nanotechnologies are with us already. Indeed, consumers are already being offered products manufactured with nanotechnologies including cosmetics, clothing, and sporting goods. But, while technology and market analysts alike expect the very small to become very big, nanotechnologies are still emerging. Like other new technologies before them, nanotechnologies may not only present potential benefits, but also potential risks. Today therefore constitutes an appropriate time to establish a dialog on nanotechnologies involving scientists, consumers, workers, industrialists, and other stakeholders. Today also represents an opportune moment to reflect on the implications of these “technologies of the tiny” for public health, health and safety at work, and the environment. Today presents us with a unique chance to set nanotechnologies on a responsible development trajectory, one that will benefit both human and environmental health and global competitiveness. The “Mapping out Nano Risks” workshop represents a modest first step—albeit an important one—towards analyzing the potential risks of nanotechnologies and what they may imply. Consequently, I should like to thank all the experts who took part in the workshop for contributing written statements prior to the workshop, for actively participating in the workshop, and for producing this timely report.