The growth mode of metallic Sn deposited onto the Au(111) surface has been investigated using Auger electron spectroscopy, low-energy electron diffraction, electron-energy-loss spectroscopy and work-function measurements for deposition at room temperature and at low temperature (−70 to −100 °C). At room temperature, Sn initially forms an alloy, AuSn, which grows laterally as a double layer, followed by continued growth of the same alloy one layer at a time. This differs from the situation for Pb and Bi on Au(111), which form an overlayer on Au before alloying. However, Sn deposited at low temperature does appear to form one layer of pure Sn followed by the growth of the AuSn alloy underneath. This latter conclusion is different from that of a previous study which suggested that Sn forms one layer of AuSn alloy covered by pure Sn layers at low temperature. The difference may be caused by different deposition rates.