The processing of the Montague Summers papers was determined by two overriding conditions: the lack of an apparent original order and the physical state of the collection. Many multi-page manuscripts had been fragmented and separated throughout the collection, and the whole shows signs of water, and subsequent mold, damage; in addition to this, there is evidence that material has been removed from the collection at some point. Prior to arrangement and description of the collection it went through a lengthy process of cleaning, as well as conservation and repair; while the collection as a whole is in good condition and stable, care should be taken in using the collection as many documents are quite fragile.
During arrangement and description, basic preservation steps taken included the removal of fasteners and clips (nearly all corroded), and interleaving acidic materials with a neutralizing micro-chamber paper.
Because of the amount of manuscript material (typed and handwritten manuscripts and letters of varying lengths), and the separate provenence of the Ellis papers, the collection was first thoroughly sorted, and as much of the separated material as possible was rejoined. As many of the individual correspondents have been identified as possible, as have the individual literary manuscripts. In many cases, this work has been quite approximate; only manuscripts and ephemera that clearly belonged to S.M. Ellis have been described as the "Stewart Marsh Ellis papers" in the final series. The identification of letters and manuscripts was helped greatly by Timothy d'Arch Smith's A Bibliography of the Works of Montague Summers (Nicholas Vane: London, 1964), and by reference to the acknowledgments of the various longer works of Montague Summers and S.M. Ellis.
For the most part, arrangement of the collection consisted of aggregating similar materials to facilitate piecing together the many fragmented manuscripts. The various levels of arrangement (series, sub-series, file, sub-file) have been applied only when necessary to assist in this task. While the longest descriptive series in the collection, the letters (of Summers and Ellis) and the manuscripts of articles and editorials, have been arranged in a basic alphabetic order, many of the series or sub-series have not been arranged beyond the grouping of similar material, such as galley proofs.