We prepared Ag thin films on SiO2/Si substrates, with and without a subnanometer-thick organic interface layer of 3-mercaptopropyltrimethoxysilane (MPTMS). The surface morphology and electrical resistivity of these films were investigated and compared. Ag films grown with an MPTMS layer were relatively flat, resulting in a smaller critical thickness. This was probably because migration of Ag atoms on the substrate was suppressed by interactions between the Ag atoms and the thiol moiety. The deposition rate and terminating group of the organic interface layer also influenced the Ag film growth.