This paper discusses ring shear tests for quantitatively measuring the adhesion between metal coatings and their substrates. Details are presented on the testing procedure and the various substrate-coating combinations that have been evaluated by this method. A number of applications are also included wherein ring shear tests have been used to define optimum cleaning/activating procedures for substrates such as 6061 aluminum, beryllium, and 304 and 440C stainless steel.