Nanotechnology is among the technologies called converging technologies, playing an important role as it enables the convergence to the nanoscale, that is to say, to the level of atoms and molecules. It is also important as part of a miniaturization trend, but more importantly because some people seek to use it for improving human performance and enhancing the human condition. Nanotechnology will have a tremendous impact considering its potentialities and the all-to-human desire for enhancement. For instance, nanotechnology based human applications on the border between therapy and enhancement- such as human implants- might represent a treat to our current conception of what defines us as humans, namely our human nature. Therefore, a different approach on the distinction between therapy and enhancement is needed. The aim of this book is to suggest such a different approach. The analysis of these issues should help shed some light in our quest for finding a better and wiser way for handling nanotechnology based human applications, and should be especially useful for anyone who may be interested in technological change and its consequences for humanity.