This chapter reviews the various strategies for scaling down phase change materials to improve device performance. It reviews the advantages of phase change nanowires (PC-NWs), top-down and bottom-up fabrication processes and characterisation techniques; technological aspects are also considered. Special focus is placed on the self-assembly of NWs by the vapour-liquid-solid mechanisms, including metalorganic chemical vapour deposition. The compositional and structural analysis of NWs is reviewed.