Various interface structures formed between Si(111) and a thick Ag overlayer are investigated by grazing-incidence x-ray diffraction. The (7×7) reconstruction of Si(111) is preserved under a room-temperature deposited Ag film. Upon annealing to 250°C the interface becomes (1×1). This is contrasted by the (3 × 3) R30°structure formed by annealing a thin Ag film on Si(111). By depositing a thick Ag film on this (3 × 3) R30°Ag/Si(111) surface at room temperature, the (3 × 3) R30°reconstruction is suppressed.