Some recent results on the effective interactions of a light gravitino with ordinary particles are reviewed. In particular, the low-energy behaviour of electron-positron and photon-photon annihilation into gravitinos are carefully discussed, and a new "low-energy theorem" is established in the electron-positron case. These results are applied to derive model independent bounds on the supersymmetry breaking scale and to organize the search for a superlight gravitino at high-energy colliders.