Emerging technologies are defined by their novelty and thus are accompanied by significant uncertainty in determining appropriate ways to manage risks associated with them. Yet, there is a body of prior knowledge about risk management and oversight policy for other technologies that have already permeated society. Here, we describe two ways in which prospective oversight policy analysis for emerging technologies can draw upon these past experiences. One involves comparing specific products that have already been marketed to similar products of the emerging technology (cognate-product approach). The other treats the emerging technology as a body of products and methods and relates it to another technological field that has already emerged and penetrated markets (whole-technology approach). In this article, we describe our work using these approaches to inform risk and oversight policy for nanotechnology and its products. We draw parallels between biotechnology and nanotechnology as whole fields of development and also between genetically engineered organisms in the food supply and agricultural products of nanotechnology. Through these comparisons, we find that both approaches to historical learning have value and present lessons that could be applied to nanotechnology.