Nanotechnology, as with many technologies before it, places a strain on existing legislation and poses a challenge to all administrative agencies tasked with regulating technology-based products. It is easy to see how statutory schemes become outdated, as our ability to understand and affect the world progresses. In this article, we address the regulatory problems that nanotechnology posses for the Food and Drug Administration’s (FDA) classification structure for ‘‘drugs’’ and ‘‘devices.’’ The last major modification to these terms was in 1976, with (...) the enactment of the Medical Device Amendments. There are serious practical differences for a classification as a drug or device in terms of time to market and research. Drugs are classified, primarily, as acting by ‘‘chemical action.’’ We lay out some legal, philosophic, and scientific tools that serve to provide a useful, as well as legally and scientifically faithful, distinction between drugs and devices for the purpose of regulatory classification. These issues we raise are worth the consideration of anyone who is interested in the regulation of nano-products or other novel technologies. (shrink)