Nanotechnology is rapidly invading many aspects of modern society - from science, research and engineering to industrial and commercial applications and, inevitably, to man and his environment. One of the biggest challenges, therefore, is managing environmental, health and safety risks of nanomaterials. Yet, the information necessary to assess their long term effects is scarce. Systematic research into what potentially makes engineered nanomaterials hazardous, how this translates into risk, and how these can be managed will be vital and involves interdisciplinary collaboration. The first International Symposium on Nanotechnology and Occupational Health, in 2004, brought together hygienists, manufacturers, toxicologists, materials scientists, regulators and researchers. It pointed the way to what needs to be done. The second International Symposium, 2005, Minneapolis, Minnesota, demonstrated the power and potential where there is a will: with nearly three times as many attendants, and with contributions from academics, industry, policymakers, non-government organizations and even lawyers, this second symposium established that, while there is international concern over how to ensure safe nanotech-workplaces, there is also progress being made in developing the required knowledge. This volume, a reprint from a special issue of the Journal of Nanoparticle Research, mainly draws from work presented at the 2005 symposium, diverse but united by the need for a holistic view of nanotechnology and risk.