Hidden Superconformal Symmetry in M Theory

The bosonic sectors of the eleven dimensional and IIA supergravity theories are derived as non-linear realisations. The underlying group includes the conformal group, the general linear group and as well as automorphisms of the supersymmetry algebra. We discuss the supersymmetric extension and argue that Osp(1/64) is a symmetry of M theory. We also derive the effective action of the closed bosonic string as a non-linear realisation.