Rotor dynamics model creation and analyses are essential parts of new machine design and development for lateral, torsional and axial vibration. These processes are also needed for addressing vibration problems or failure investigations for equipment in service.Lack of sufficient experience by analysts can result in creation of vibration mathematical models that are inadequate for these purposes. Reliance on sophisticated analytical tools that are commercially available will not help achieve needed accuracy of results if inadequate model data are used. This book focuses on large high speed turbine-generators as are they are difficult to model. Information provided gives guidance for preparing suitable models, defines analysis methods and interpretation of vibration results. Numerous case studies are provided showing model creation and definition and corresponding torsional and lateral vibration results. Expected accuracy of vibration predictions is provided. Processes such as high speed balancing and fatigue life consumption estimation is discussed in detail. Reference is made to relevant domestic and international vibration standards.