A contact theory for both normal and shear behavior of contacting surfaces under elastic and no-slip conditions was examined by laboratory experiments using hollow cylindrical granite samples upon which surfaces of different roughnesses were prepared. The surfaces were placed in contact in a torsional-loading apparatus, and both their normal closure and deformation in shear were measured. To compare with the theoretical prediction, the shear experiments were done under very low shear stress assuming no-slip at the real contacts: we measured shear stiffness of the contacting surfaces under various normal stresses up to 35 MPa. The theoretical predictions, based on profilometry data from the surfaces, generally show quantitative agreement with the mechanical measurements: the normal joint closure increases nonlinearly with normal stress and shows larger deformation for the rougher surface. The shear stiffness of contacting surfaces also increases nonlinearly with normal stress and is larger for the smoother surface. A poorer fit was obtained for the smooth surface which seems due to the limitation of resolution in our topography measurements and minor anelastic behavior which occurred at the real contacts. The micromechanical approach presented here may open a way to physical understanding shear contact properties, such as shear wave propagation across interfaces and friction. ¿ American Geophysical Union 1989