We show that multilayers of a common polyoxometalate-silicotungstic anion (STA), alpha-SiW12O404- -are formed on a Ag electrode surface or other electrode surfaces in the presence of Ag+ poised in the cathodic potential region. This effect is not observed on either Au surfaces or C surfaces absent Ag+. Surface X-ray scattering, quartz crystal microbalance, X-ray photoelectron spectroscopy, and scanning tunneling microscopy measurements show that the silicotungstic acid apparently stabilizes the Ag+ cation, which electrostatically assembles with the STA anion or the one-electron reduced species to form ordered multilayers. In contrast to other electrostatically assembled multilayer systems, those formed here exhibit considerable order.