The electrodynamic response in the normal and superconducting ground states of K 3 C 60 and Rb 3 C 60 is reviewed. The normal state optical properties are rather unconventional since they can be explained only by considering the interplay of a Drude-like and a mid-infrared absorption component. On the other hand, the superconducting state optical properties are more straightforward since they display clear fingerprints related to the conventional weak coupling limit of the BCS ground state. Our optical spectra clearly display a well developed excitation due to the superconducting gap. Moreover, the analysis of our optical results in the superconducting state within the standard Eliashberg electron–phonon theory of superconductivity strongly supports a pairing mechanism mediated by high frequency intramolecular phonon modes.