This paper presents a second-order model for synchronous machines that can be utilized in power system dynamic performance analysis and control design tasks. The model has a similar structure to the classical model in that it comprises two dynamic states, the power angle and the angular speed. However, unlike the classical model, the model finds applications beyond first swing stability analysis; for example, they can also be utilized in transient stability studies. The model is developed through a systematic model-order reduction of a nineteenth-order state-space model by using singular perturbation techniques. It is validated by comparing its response with that of the nineteenth-order model and that of the classical model.