A model is constructed to analyze the effects or normal and tangential loading on elastically identical coated spheres. The solution for a tangential displacement applied to a circular patch on the coated surfaces, including the occurrence of micro-slip (either full or partial slippage), is derived. If it is assumed that the slip region is a circular annulus of inner radius c, then the following two sets of approximations can be made: a "stiff" approximation that satisfies the zero micro-slip condition exactly for the inner circle and a "soft" approximation that satisfies the Amontons-Coulomb frictional law exactly for the slip region. It is concluded that the "soft" approximation gives an accurate value for the symmetric traction component, 1 2[τzr1(1)-τzθ1(1)], induced by the normal and tangential loads. © 1990.