This subseries contains Meyer's correspondence during his years as ambassador to Italy. Included are letters describing the court of Victor Emmanuel III, as well as considerable political correspondence with Henry Cabot Lodge and others discussing Meyer's abortive candidacy for Congress in 1902, the annual gubernatorial contests in Massachusetts, 1901-1904, and the presidential election of 1904.

This subseries contains Meyer's correspondence during his ambassadorship to Russia. His long letters to Theodore Roosevelt, Secretary of State John Hay, and Henry Cabot Lodge detail the progress of the Russo-Japanese War from the Russian vantage point and Meyer's intense peace negotiations with the tsar and his government. Roosevelt's letters to Meyer discuss world politics and the Russian-Japanese diplomatic tangle. Also described in Meyer's correspondence are the revolutionary outbreaks against the Russian absolutist regime in 1905-1906 and the early history of the Duma, the Tsarist parliamentary experiment.

This subseries contains Meyer's papers from his years as Postmaster General. The bulk of the papers concerns the campaign for parcel post and the long and ultimately unsuccessful struggle for legislative enactment of the postal savings bank system, a pet project of Meyer's. Also included is considerable material on politics and the distribution of postmasterships. Among the most notable letters are those to and from Theodore Roosevelt, William Howard Taft, Henry Cabot Lodge, Patrick M. Longan, and others discussing preparations for the Taft nomination and assessing Republican prospects in various sections of the country. Included are a few letters from Booker T. Washington, 1908, about political intelligence from Alabama.

This subseries contains papers from Meyer's tenure as Secretary of the Navy under Taft. The correspondence is largely bureaucratic, dealing with such matters as appropriations, shipbuilding contracts, and work done at various American navy yards (especially Boston, Mass. and Portsmouth, N.H.). Major correspondents include William Howard Taft, Meyer's Assistant Secretary Beekman Winthrop, and Admirals William S. Cowles, Charles S. Sperry, William Swift, and Richard Wainwright. Included are a few political letters to and from Taft, Henry Cabot Lodge, and Theodore Roosevelt, as well as letters from Roosevelt about big-game hunting. Because of a serious case of typhoid contracted by Meyer, the subseries contains few papers related to the pivotal election of 1912, in which Meyer backed Taft over his friend Roosevelt. A few letters reflect Meyer's dismay over the Roosevelt candidacy.

Among the individual items of importance in this subseries are: a copy of a lengthy letter from President Taft to his son, Robert A. Taft, in 1911 reporting on political developments; two 1908 letters dealing with Meyer's role in the return of Eleanor Medill "Cissy" Patterson's daughter, who had been abducted and brought to Russian Poland by her Polish father; and a 1910 letter from Meyer to his wife describing an inspection trip to the United States Naval Base at Guantanamo, Cuba.

This subseries contains general business correspondence, letters on politics to and from Theodore Roosevelt, and notes and other papers about naval preparedness prior to America's entry into World War I.

This subseries consists of 33 letterbooks of Meyer's personal and official correspondence during his years as Postmaster General and Secretary of the Navy, as well as four additional letterbooks of business and political correspondence.

These press books contain legislative proposals, memoranda, press releases, and speeches from Meyer's tenure as Postmaster General and Secretary of the Navy.

This subseries contains 21 scrapbooks of newspaper clippings covering Meyer's service as ambassador to Italy, ambassador to Russia, Postmaster General, and Secretary of the Navy (Vol. 40-60); and two scrapbooks dealing with military preparedness in America during World War I, the policies of Josephus Daniels as Secretary of the Navy, Theodore Roosevelt's return to the Republican Party, and the election of 1916 (Vol. 61-62). Volumes 41-43 describe the negotiations leading to the Portsmouth Treaty and peace between Russia and Japan, 1905; the often violent disturbances inside Russia, 1905-1906; and the opening of the Duma.

This volume contains a printed genealogy of the Von Lengerke family, compiled in German, with later annotations on the Meyers family.

This volume contains an inventory of the second floor of the Palazzo Brancaccio, Meyer's Italian ambassadorial residence, prepared in Italian by Carlo Brancaccio.