The basic concept and the fracture mechanics methods for determination of the fracture energy and the fracture resistance of interfaces between semi-brittle materials are reviewed. The interfacial fracture energy is derived from the global energy balance concept for crack propagations in an interface, whereas the fracture resistance parameter is based on continuum mechanics models of an interface crack. The method to determine the strength parameters of an interface consists of stress analyses and mechanical tests on pre-cracked specimens of a simple geometry such as layered-bonded bend test specimens.