The idea that there was a Copper Age between the Neolithic and Bronze Age was inspired by the discovery of copper use in prehistoric North America. Its currency in European prehistory owes much to the 1861 observations by William Wilde that copper artefacts preceded bronze tools in Ireland, though he himself did not postulate a Copper Age per se. Acceptance of the existence of a Copper Age was a long process, not least as it seemed to contradict the premises of the Three Age System and was conflated with arguments for the local development of copper metallurgy, but the 1876 and 1880 international prehistoric archaeology congresses were key moments in its recognition. By the mid-1880s its validity was widely accepted in Europe. In contemporary dating schemes, the definition of the Copper Age varies according to regional and national traditions. The paper touches on the debate concerning the use of technological stages as chronological periods and examines alternative conceptualisations of the early periods of metallurgy in Europe.