A new approach to the evaluation of the coating-substrate interface strength is presented. Tt implies an energy-related consideration of solid-state deformation processes under the action of a penetrating indenter. The required experimental data are gained from load-indentation measurements. The interface strength is quantified in terms of a specific interface deformation energy accumulated into the interface deformation in the course of the indenter’s penetration. The theoretical approach was examined in relation to cathodic-arc-deposited and magnetron-sputtered TiN coatings on high speed steel substrates as well as in relation to Al coatings on glazed Al2O3. The results were shown to be in agreement with conventional characterization methods.