Summary: We present a computational procedure for studying collisions of multibody systems. It combines the procedures of impact analysis and the methods of modern multibody dynamics (including the use of Kane’s equations, lower body arrays, generalized speeds, and differentiation algorithms). By assuming the duration of impact to be very short and that the configurations of the systems have only small changes during the colliding process, we can automatically generate the governing dynamical equations. By using Newton’s impact law, the partial velocities of contact points determine impulse force components. Then, by back substituting into the governing equations, the changes of velocities during the collision, the components of internal impulses, and the subsequent motions of the systems after collision can be determined.