Symmetry reduction techniques exploit symmetries that occur during the execution of a system, in order to minimize its state space for efficient verification of temporal logic properties. This paper presents a framework for concisely defining and evaluating two symmetry reductions currently used in software model checking, involving heap objects and, respectively, processes. An on-the-fly state space exploration algorithm combining both techniques is also presented. Second, the relation between symmetry and partial order reductions is investigated, showing how one’s strengths can be used to compensate for the other’s weaknesses. The symmetry reductions presented here were implemented in the dSPIN model checking tool. We performed a number of experiments that show significant progress in reducing the cost of finite state software verification.