Of several available methods for the measurement of the thermal resistivity of soils, the thermal needle method and the Shannon and Wells method are considered most suitable, because of their relative simplicity and the short measurement time required. The thermal needle method is the simpler of the two, and it offers the added advantage that knowledge of the specific heat of the soil is not required for calculation of the thermal resistivity from the test data. A special thermal needle design and simple test procedures have been developed which make possible the determination of thermal resistivity in both the radial and axial directions and the specific heat for a given sample.