Ever since records began, accounts of other peoples and their institutions and customs have included comments about their mental characteristics. The present article traces this feature from the 18^th century to roughly the First World War, with a brief sketch of more recent developments. For most of this period two contrasting positions prevailed: the dominant one attributed human differences to ‘race’, while the other one explained them in terms of psychological, environmental and historical factors. The present account focuses on the latter, among them those who asserted ‘the psychic unity of mankind’. Generally it is shown that from the early period when writings were based almost entirely on secondary sources, to the beginnings of empirical studies, ethnological theories were indissolubly linked to psychological concerns.