The science and engineering field of nanotechnology develops new materials at the molecular scale (1 nanometer equals 1 billionth of a meter) where they display novel exploitable physical, chemical, and/or optical properties. Development programs for these materials, devices, and systems are in progress in over 70 countries worldwide. Nanotechnology has attracted social theoretical attention as both an object and a field. Nanotechnologies have drawn fascinated attention as nascent risk objects, and their promised utility for human cognitive and physical enhancement in particular has accelerated societal debate about cryonics, cyborgs, and technological implications for aging. This entry traces the main contemporary social theory entanglements in nanotechnology studies, asking how they revise the understanding of a field, the social study of the future more broadly, and cyborg and aging futures specifically, along with risk and public participation.