In this chapter, a methodology for automatic generation of the equations of motion for rigid multibody systems is reviewed. The methodology is based on two formulations: body-coordinate formulation that uses Newton-Euler equations; and joint-coordinate formulation that employs relative coordinates. A systematic transformation process from the body into the joint-coordinate formulation is described. This methodology provides an effective and efficient formulation for constructing the equations of motion for multibody systems, in general, and for robotic devices in particular. A simple example is provided to demonstrate the implication of the methodology. In the final section, a list of some available commercial and free multibody dynamic software is presented.