We demonstrate, for the first time, the trapping and manipulation of individual silicon nanowires by light-induced dielectrophoresis, or Optoelectronic Tweezers (OET). Optical manipulation provides a powerful means to bridge the micro and nano worlds. Optical tweezers have been used to trap single silicon and CdS nanowires, However, their ability to perform parallel assembly is hampered by the high optical power density (10^7 W/cm^2) and small working area (~1umx1um). Dielectrophoresis can trap nanowires between two fixed microelectrodes, however, it lacks the resolution to manipulate single nanowires and the trapping sites are fixed by the electrode pattern. In contrast, OET is capable of manipulating a large number of microparticles or cells over a large area. Previously, the smallest particles that OET could trap individually were limited to 2 um. In this paper, we report on the trapping of single Si nanowires with diameters of 100 nm using OET with an optical power density of 100 W/cm^2. We show that OET can separate two nanowires that are 4um apart, and transport a single nanowire at a speed of 68 um/sec. Array patterns of silicon nanowires have also been demonstrated.