Se and Te nanowires (NWs) are spontaneously formed in solution through chemical decomposition of stabilizer-depleted nanoparticles (NPs) in the presence of a strong complexing agent. Highly crystalline Se and Te NWs with monodisperse lateral sizes, in the range 10-100 nm, are produced (see Figure and cover). This work provides a new approach to nanoscale synthesis, which takes advantage of the transformation of NPs to NWs induced by stabilizer shell depletion and ensuing chemical reactions.