A method to predict the ultimate adhesion performance of coatings subjected to biaxial, tensile stress is presented. A set of equations is developed to predict the onset of failure when the locus of failure is cohesive in the coating. The equations also have been extended to predict fatigue lifetime when a coating is cycled from a low temperature to room temperature. To test these equations, the Edge Liftoff Test (ELT) was developed. It consists of fabricating coatings of various heights on a rigid substrate and dicing the latter, so that the edges are 90 degrees to the interface. The parts are cooled and the temperature of debonding is recorded. For thermal fatigue validation, cycles at which the first debond is observed are recorded. ELT results have been collected for a typical epoxy for both monotonic and cyclic cooling. The predictions are in agreement with results.