Like all technologies, nanotechnology will inevitably present risks, whether they result from unintentional effects of otherwise beneficial applications, or from the malevolent misuse of technology. Increasingly, risks from new and emerging technologies are being regulated at the international level, although governments and private experts are only beginning to consider the appropriate international responses to nanotechnology. In this paper, we explore both the potential risks posed by nanotechnology and potential regulatory frameworks that law may impose. In so doing, we also explore (...) the various rationales for international regulation including the potential for cross-boundary harms, sharing of regulatory expertise and resources, controlling protectionism and trade conflicts, avoiding a “race to the bottom” in which governments seek economic advantage through lax regulation, and limiting the “nano divide” between North and South. Finally, we examine some models for international regulation and offer tentative thoughts on the prospects for each. (shrink)