Group Manifold Approach to Supergravity

We present a short review of the group-geometric approach to supergravity theories, from the point of view of recent developments. The central idea is the unification of usual diffeomorphisms, gauge symmetries, and supersymmetries into superdiffeomorphisms in a supergroup manifold. The example of N = 1 supergravity in d = 4 is discussed in detail and used to illustrate all the steps in the construction of a group manifold action. In the Appendices, we summarize basic notions of group manifold geometry and of integration on supermanifolds.