Impeller blades in a centrifugal compressor stage operate in an unsteady pressure field due to the presence of a downstream diffuser. This unsteady pressure or loading is more generally the result of what is referred to as the “impeller-diffuser” interaction. The primary result of this interaction is to set up pressure waves which traverse and decay from the trailing edge to leading edge of the blades. It is these unsteady pressure waves which are thought to be the primary driver of whether an indicated resonance on a Campbell diagram will achieve resonance or not. Both frequency and shape of the forcing are important in determining whether a blade will encounter aeromechanic difficulty. A goal of this research is to delineate (design and operating) parameters that set impeller blade aerodynamic and structural response; this is then to be followed by defining what constitutes an adequate characterization of impeller blade system response so that it can be used to develop guidelines for avoidance of aeromechanic difficulties in centrifugal compressor stages.