This paper describes the functionalization of the surfaces of gold nanoshells, which consist of silica nanoparticles coated with a continuous thin layer of gold. Previous studies have shown that gold nanoshells exhibit optical properties similar to those of metal colloids (e.g., strong optical absorptions and large third-order nonlinear optical polarizabilities). In contrast to metal colloids, however, the plasmon resonance of the nanoshells can be tuned to specific wavelengths across the visible and infrared range of the electromagnetic spectrum by adjusting the relative size of the dielectric core and the thickness of the gold overlayer. In efforts to develop new strategies for protecting and manipulating these nanoparticles, this paper describes the functionalization of the surfaces of gold nanoshells with self-assembled monolayers derived from the adsorption of a series of alkanethiols. The nanoshells are characterized by transmission electron microscopy, UV−vis spectroscopy, FTIR spectroscopy, Raman ...