A large part of the collection consists of correspondence with British, Continental and North American correspondents, notably Ignaz von Dllinger, Richard Simpson and Thomas Frederick Wetherell. Other correspondents include W.E. Gladstone and his family, J.H. Newman and many of the bishops associated with the minority at the First Vatican Council. There are also large groups of letters sent between Acton's immediate ancestors, and between Acton and his own family. In addition to correspondence, the collection contains a wide range of biographical, financial and legal papers.
MS.Add.8119/1-6: General letters, mostly to Acton.
MS.Add.8119/7: Correspondence, mostly between Acton and Richard Simpson, Sir Rowland Blennerhassett, Lady Charlotte Blennerhassett and Henry Nutcombe Oxenham, with related material.
MS.Add.8119/8: Correspondence between Thomas Frederick Wetherell and Acton, with related correspondence; miscellaneous correspondence and papers, including material relating to parliamentary elections.
MS.Add.8119/9: Correspondence between Acton and members of the Gladstone family; school notes taken by Acton; diaries, journals and passports of Acton and Marie Acton; an incomplete biography of Sir John Francis Edward Acton, apparently by Annie Acton; recollections of her family by Mary Elizabeth Anne Acton.
MS.Add.8120/1: Letters, mostly to Acton, from foreign correspondents.
MS.Add.8120/2: Correspondence, mostly between Acton and Johann Joseph Ignaz von Dllinger, but including letters between these and other correspondents.
MS.Add.8121/1-2: Correspondence and legal papers concerning members of the Acton family, eighteenth and nineteenth centuries.
MS.Add.8121/3: Acton family letters, accounts and papers, mostly financial, seventeenth and eighteenth centuries; correspondence of Mary Anne Acton and Sir Richard Acton; miscellaneous papers.
MS.Add.8121/4: Acton family letters, accounts and papers, mostly financial, seventeenth and eighteenth centuries; correspondence of Mary Anne Acton, Elizabeth Throckmorton and Sir Richard Acton.
MS.Add.8121/5: Letters to Mary Anne Acton, Sir Richard Acton and others, mostly from members of the Acton family; miscellaneous legal and other papers.
MS.Add.8121/6: Letters, mostly to Acton and members of his family.
MS.Add.8121/7: Correspondence, etc., mostly between members of the Acton and Arco-Valley families, notably Anna Margareta Arco-Valley.
MS.Add.8121/8: Letters, mostly from Marie Acton to Baron Acton.
MS.Add.8121/9: Correspondence, mostly between Acton and his children Annie Acton and Richard Maximilian Dalberg Acton.
MS.Add.8121/10: Correspondence between Acton and Richard Maximilian Dalberg Acton; papers of Annie Acton, including material for a history of the Acton family.
MS.Add.8121/11: Letters from Mary Elizabeth Anne Acton to Acton; miscellaneous Acton family correspondence.
MS.Add.8122/1: Notes by Acton on various subjects; miscellaneous items.
MS.Add.8122/2: Miscellaneous notes, letters and legal documents; typescript copies of letters from Acton to Ignaz von Dllinger.
MS.Add.8122/3-4: Miscellaneous notes, letters and legal documents.
MS.Add.8123/1: Financial, legal and miscellaneous letters and documents, mainly concerning Acton and members of the Acton and related families, mostly nineteenth century.
MS.Add.8123/2: Financial and personal papers of Acton and his family.
MS.Add.8123/3: Press cuttings concerning Acton, his published works and his family; used envelopes.