Lead-isotope and neutron-activation analyses reported for Greek Bronze Age lead and silver artifacts prove that mines at Laurion were being exploited for silver, lead being produced as a by-product, from at least as early as Middle Heiladic times, continuing into the Late Helladic IIIC1 period. The analyses show that the Laurion was the dominant, almost exclusive, source of these metals for the Mycenaean cultures, and they provide an estimate of the minimum silver content necessary in argentiferous lead to make it economically or technically possible to extract the silver by cupellation in Bronze Age Greece.