Abstract: Dynamics simulation of smooth surfaced rigid bodies in contact is a critical problem in physically based animation and interactive virtual environments. We describe a technique that uses reduced coordinates to evolve a single continuous contact between smooth piecewise parametric surfaces. The incorporation of friction into our algorithm is straightforward. The dynamics equations, although slightly more complex due to the reduced coordinate formulation, can be integrated easily using explicit integrators without the need for constraint stabilization. Reduced coordinates confine integration errors to the constraint manifold, thereby permitting a wide choice of step sizes with visually acceptable results. We demonstrate these results using Loop Subdivision surfaces with parametric evaluation.