  We construct a topological theory for euclidean gravity in four dimensions,
by enforcing self-duality conditions on the spin connection. The corresponding
topological symmetry is associated to the SU(2) X diffeomorphism X U(1)
invariance. The action of this theory is that of d=4, N=2 supergravity, up to a
twist. The topological field theory is SU(2) invariant, but the full SO(4)
invariance is recovered after untwist. This suggest that the topological
gravity is relevant for manifolds with special holonomy. The situation is
comparable to that of the topological Yang-Mills theory in eight dimensions,
for which the SO(8) invariance is broken down to Spin(7), but is recovered
after untwisting the topological theory.
