Abstract: A comprehensive discussion of the formulation of supergravity theories in superspace is presented. After reviewing the general formalism and the linearized theory, we exhibit a complete solution to the Bianchi identities for all N. This solution still contains a reducible representation of supersymmetry and further constraints are imposed to obtain off-shell conformal supergravity (N ⩽ 4). N = 1 and 2 off-shell Poincaré supergravities are rederived from the corresponding conformal theories. On-shell Poincaré supergravity is discussed for all N in superspaces with additional bosonic coordinates.