The decay processes of metallic lanthanum after resonant 4d to 4f excitation by synchrotron radiation have been studied by means of electron spectroscopy. Excitation to the 4d⁹4f¹(³D₁) state, which is below the 4d ionization threshold, was found to decay predominantly through N_4,5O_2,3O_2,3 and N_4,5O_2,3V spectator resonance processes. The energy shift relative to the corresponding normal Auger energies was 1.6+or-0.3 eV in the case of NOO resonance Auger decay, whereas no energy shift was found for the NOV resonance Auger electrons. The excitation to the main 4d to 4f giant resonance was found to decay through autoionization leading to a one-hole final state 5s^-1 or 5p^-1, or through normal Auger processes. Autoionization processes are strong on the low energy side of the resonance, but when the excitation energy increases, normal Auger processes become more and more dominant, indicating a change in the nature of the giant resonance.