The goal of the SimTK Simbody project is to make robust, high performance multibody dynamics technology available to anyone working in biosimulation. This allows modelers to choose the best set of mechanical coordinates for the job, without having to worry about the resulting technical issues. I will provide an introduction to the scope and capabilities of multibody models in general, and the SimTK Simbody implementation in particular, emphasizing application in coarse-grained molecular simulations. I'll discuss what is available today, what is planned for Simbody 1.0, and how this fits in to the bigger biosimulation picture.