A large part of the collection consists of correspondence with British, Continental and North American correspondents, notably Ignaz von Döllinger, 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.