The first series, planned by Lord Acton and edited by him with Stanley Mordaunt Leathes, Sir Adolphus William Ward and G. W. Prothero, was launched in 1902 and totalled fourteen volumes, the last of them being an historical atlas which appeared in 1912.

A second series, with entirely new editors and contributors, The New Cambridge Modern History, appeared in fourteen volumes between 1957 and 1979, again concluding with an atlas.

[2][3] The original Cambridge Modern History was planned by Lord Acton, who during 1899 and 1900 gave much of his time to coordinating the project, intended to be a monument of objective, detailed, and collaborative scholarship.

[4] Acton was Regius professor of modern history at Cambridge, and a fellow of All Souls, Oxford.

[5] The new work was published in fourteen volumes between 1902 and 1912, in the British Isles by the Cambridge University Press and in the United States by Macmillan & Co. of New York City.