Human enhancement, the idea that through biomedical technologies, human bodies and minds can be made faster, stronger and longer-lasting - better, in fact, than human - has emerged in recent years as a significant conceptual and cultural force. A wide range of existing biomedicines, including Prozac, human Growth Hormone, Ritalin and Botox are considered to be enhancing or to have enhancement uses. The idea of human enhancement is also shaping the development of new technologies aimed at improving human cognitive capacities or extending lifespan. This paper traces the origins of the idea of human enhancement, as something distinct from the standard therapeutic use of medical technology, to the bioethical debates on gene therapy. This original formulation draws heavily on the idea of an acultural, biological body described through instrumental measurement and acted upon by value-neutral technologies that can be put to good or bad uses by social actors. Drawing on the broadly constructionist approach of Science and Technology Studies (STS), the limitations in this framing of enhancement as a category for understanding technologies will be examined. The limitations of the current model of enhancement and the potential for novel insights provided by an approach paying greater attention to the social shaping of technologies will be illustrated using examples from the case of human Growth Hormone. I argue that these considerations are important because the concepts of enhancement and therapy are pertinent not only to the study of contemporary technologies, but also to the future development of novel biotechnologies.