Three different hard surface coatings, that is, TiN, so-called diamond-like carbon (DLC) on steel substrates, and polycrystalline diamond on cemented carbide substrates, have been tested and compared under conditions of low-amplitude fretting. The displacement amplitudes were chosen to cover the partial slip regime and the lower part of the gross slip regime, with some emphasis on identifying the critical conditions for incipient gross slip (IGS). A giantmagnetostrictive actuator has been used, allowing extremely well-controlled testing conditions, typical of the partial-slip fretting regime. The relative displacement between the vibrating specimens was measured with an optical technique, capable of a resolution of 2 nm. The displacement and the tangential forces active in the contact surface were recorded as functions of time. Based on these data, post-experiment off-line computation was used for identifying IGS parameter values. Two- and three-dimensional fretting maps were constructed. The fretting scar morphology was studied by scanning electron microscopy. Fretting mechanisms were clarified by comparisons between the recorded test data and the structural damage revealed by the surface studies.