This Recommended Practice (RP), IEST-RP-NANO205.1: Nanotechnology Safety: Application of Prevention through Design Principles to Nanotechnology Facilities, provides facility design information intended to minimize risks for personnel associated with nanotechnology research and production. Using NIOSH “Prevention through Design” principles, the RP addresses safety issues related to incoming materials, products, processes, and byproducts. Methods of risk mitigation are suggested. Facility design and response systems are described for normal operation as well as external and internal emergency. Information is provided to assist in the development of an effective nanotechnology environmental health and safety program. This document is useful to all those involved in facilities that develop or use nanomaterials.