Letter books were created to preserve copies of incoming and outgoing diplomatic correspondence, which constituted the working files documenting the day-to-day diplomatic business of the Republic of Texas with all other nations. These are five letter books containing copies of correspondence between the Department of State and Texan and foreign diplomatic and consular representatives, dating 1836-1846. Subjects discussed focus on relations between Texas and various foreign countries, including negotiations for loans, and treaties of commerce and recognition, particularly a treaty with Mexico. Three of the volumes contain copies of incoming correspondence, 1836-1846 (with indexes in two of them); two of the volumes contain copies of outgoing correspondence, 1839-1846 (one of which has an index).

United States diplomatic correspondence was created in the course of conducting diplomacy between the Republic of Texas and the United States of America, in which Texas sought recognition, aid, and annexation into the Union. These are chiefly letters received by the Department of State from commissioners and agents to the United States, and copies of letters to the Secretary of State and commissioners to others. Also included are some commissions and appointments and correspondence of the Department of State with U.S. representatives to Texas. In addition, there are two volumes containing letters and dispatches sent by the Texas Legation in Washington, D.C. (1839-1845). Overall dates covered are 1831-1832 and 1835-1846. Subjects covered include instructions of the Secretary of State to commissioners and instructions of commissioners to agents appointed by them. Also discussed are Indian affairs, recognition and annexation of Texas by the United States, negotiations for loans, settlement of claims between the two countries, negotiations for duties, extradition, boundaries, and general information on relations with the United States and activities there as reported by the commissioners. Correspondents include Stephen F. Austin, David G. Burnet, Anson Jones, William Bryan, Samuel P. Carson, William H. Wharton, James P. Henderson, Robert A. Irion, Memucan Hunt, Abner S. Lipscomb, John Forsyth, Alcee L. LaBranche, Richard G. Dunlap, James Reily, Joseph Waples, Joseph Eve, Isaac Van Zandt, John C. Calhoun, Ebenezer C. Allen, Charles H. Raymond, and Andrew J. Donelson.

English diplomatic correspondence was created in the course of conducting diplomacy between the Republic of Texas and Great Britain. This series consists chiefly of correspondence with Texas representatives in England and with British secretaries of state for foreign affairs, Lords Palmerston (1830-1841) and Aberdeen (1841-1846), covering the years 1837-1846. Subjects covered include instructions from the Secretary of State to Texas representatives and their reports of activities back to him, claims against Texas for captured British vessels, commercial agreements, recognition of Texas independence, relations with Mexico, protection of British subjects in Texas, slavery and the slave trade, the Texas blockade of Mexican ports, and Texas' annexation to the United States. Correspondents include Lords Aberdeen and Palmerston, James Hamilton, Ashbel Smith, James P. Henderson, Richard Pakenham, and Charles Elliott. Approximately two-fifths of the original English diplomatic correspondence has been dispersed over the years to other series, including many of the papers relating to Mexican affairs, which were placed in the series Correspondence relating to diplomatic relations with Mexico. At some time transcripts from the British Public Records Office of correspondence between the Foreign Office and its representatives relating to Texas were added to the file. These have since been removed and placed in a manuscript collection called Great Britain, Foreign Office records.

French diplomatic correspondence was created in the course of conducting diplomacy between the Republic of Texas and France. This series consists chiefly of correspondence between the Department of State and agents of the Republic of Texas in France, and French chargé d'affaires in Texas, Alphonse de Saligny (1840-1842, 1844-1846) and Jules Edouard de Cramayel (1842-1844). Also present are copies of correspondence between French foreign ministers Louis Mathieu, Count Molé (1836-1839), and Francois Pierre Guillaume Guizot (1840-1848); and Texan representatives and the Texas Department of State. Dates covered are 1838-1846. Subjects covered include instructions of the Department of State to its agents, letters of appointment, attempts to obtain commercial treaties, recognition of Texas independence by the French government, negotiations for a treaty of recognition with Spain, attempts to have France negotiate a treaty of peace and recognition between Texas and Mexico, and establishment of regular mail service between France and Texas. Correspondents, in addition to those previously listed, include Ashbel Smith, James Hamilton, James P. Henderson, Robert A. Irion, George S. McIntosh, and Anson Jones. A small number of letters have been added at some time, from another file transferred in 1905 as Miscellaneous French manuscripts, as well as from the Secretary of State records series called Domestic correspondence.

The documents in this series were created in the course of conducting diplomacy between the Republic of Texas and Belgium, the Netherlands, Hanse towns, Spain, and the Papal States. These records consist of correspondence of the Secretary of State primarily with Texan representatives to Belgium, the Netherlands, the Hanse towns (or Hanseatic League), and Spain. Also included is a letter book of correspondence of William Henry Daingerfield, Texas chargé d'affaires to the Netherlands, Belgium, and the Hanseatic League, dating January 20, 1843-August 27, 1845. Overall dates covered are 1842-1846. Subjects concern the recognition of Texas in these countries and Texas' attempts to obtain treaties of amity and commerce. Also present are a few letters of credence. Correspondents include James Hamilton, V. Pierson, Ashbel Smith, W. Henry Daingerfield, and others.

Documents in this series were created in the course of attempting to conduct diplomacy between the Republic of Texas and the Republic of Mexico. This series consists chiefly of correspondence between the Secretary of State and Texas commissioners to Mexico; and with diplomatic representatives to Great Britain relating to negotiations with Mexico. Also present is some correspondence of the President with Mexican officials. Dates covered are 1835-1845 and undated. Subjects concerned include attempts to negotiate a treaty with Mexico, Mexican invasions of Texas, Texas prisoners in Mexico, negotiations with Yucatan for use of the Texas Navy, and the treaty of peace between Yucatan and Mexico. A few documents relate to domestic affairs, particularly Indian relations and the depreciation of Texas currency. Correspondents include David G. Burnet, Mirabeau B. Lamar, Antonio Lopez de Santa Anna, James Webb, James Treat, Richard Pakenham, Barnard Bee, and Silas Wright. At some point a small number of documents were transferred from this series to the series Correspondence relating to diplomatic relations with Yucatan.

The documents in this series were created in the course of conducting diplomacy between the Republic of Texas and the rebellious Mexican state of Yucatan. This series consists of correspondence of the Secretary of State, the President, and Edwin W. Moore, Commander of the Texas Navy, with the Secretary of War and Marine of the State of Yucatan. The treaty of the Republic and Yucatan, by which Texas agrees to furnish naval support to Yucatan's revolution, is also included. Photostats and typed copies of letters are included with the original documents. Dates covered are 1840-1842. Correspondents include Commodore Edwin W. Moore, Colonel Martin F. Pereza, Joaquin G. Rejon, and Pedro Lumas. This series was not originally part of Diplomatic correspondence, but was created at an unknown date by removing materials from two series-- Correspondence relating to diplomatic relations with Mexico, and Miscellaneous manuscripts and documents written in Spanish, French, and German.