Abstract: In designing a foundation subjected to coupled sliding and rocking vibration, four parameters Kx, K , Cx and C are indispensable. For a long time, designers have often used either the formulae from the half-space theory or other procedures such as the superposition method or approximate one to obtain these parameters. In this paper, the method, called "Phase Method", is presented. According to this new method, the requisite parameters can readily be determined from a small-scale test foundation excited with a mechanical vibrator provided that two phase angles and two amplitudes are measured. General and simplified formulae are shown. A case history is also described.