Operating deflection shape (ODS) analysis is a vibration testing and analysis procedure that is capable of producing animations of the deformation characteristics of a vibrating mechanical system at any discrete frequency. The ODS analysis provides information regarding movement during operation that can be made into an animation. The animations can be extremely helpful in defining areas of structural weakness or identifying areas of mechanical “looseness”. In cases of resonant excitation, the operating deflection shape animation will provide an estimate of the mode shape for the natural frequency that is being excited. A general overview of ODS testing techniques, analyzer set-up and model development is presented along with case studies to illustrate the benefits of operating deflection shape animations in root-cause vibration analysis.