AbstractEngineered nanomaterials have structured compo-nents less than 100 nanometers or 0.1μm in greatest diameter. Products with nanomaterials as their basis are diverse, includ-ing diagnostic and therapeutic agents, stain-resistant clothing, solar cells, sun blocks, and cosmetics, and an expanding array of applications is anticipated. The increasing production and use of engineered nanomaterialsmay lead to greater exposures of workers, consumers, and the environment, and raises con-cerns about potential harms to human and ecosystem health. This paper addresses the general topic of research on engineered nanomaterials, health, and the environment. It covers the history of research planning on engineered nanomaterials, giving emphasis to the recent reports from a committee of the US National Research Council. The two reports from this committee offered a framework-based re-search strategy intended to address critical uncertainties. This paper ends with general lessons learned from experience with engineered nanomaterials that may apply to other emerging environmental threats. Keywords Nanotechnology. Research strategies.Human health.Environmental health and safety. Risk assessment