Materials accessioned prior to 1991 were processed on receipt. The September 10, 1991 and May 19, 1992 accessions were processed January-June, 1996 when the other processed materials were integrated into the collection, and a new finding aid was prepared.

Initial Subject File Processing: Working at the Physics Department under the direction of University Archivist Maynard Brichford, Tonya Lillie refoldered the material into acid-free folders, retaining the original arrangement of the folders and transcribing the original folder titles. Folders were assigned individual two-part sequential numbers, keyed to the number or letter of the original file cabinet drawers or boxes in which they were stored and to the number of the folder within that drawer or box. The Physics Department then prepared a "Master Index," providing a drawer-by-drawer inventory of Bardeen's file folders in their original order, and listing drawer number, folder-title, date and, in some cases, brief comments on folder contents.

On September 10, 1991, 48 cubic feet of Prof. Bardeen's papers were transferred to the University Archives and processing was conducted intermittently from October, 1991 through June, 1994. By June 1994, Brichford had identified four major groupings of files within the Bardeen Papers: publications, dissertations, correspondence, and subjects. He arranged chronologically the publications, dissertations, correspondence, and approximately one-quarter of the subject files. He had also begun to supply more descriptive folder titles and to assign more precise dates to folders in the subject files. Brichford and graduate assistant Ellen Swain produced a folder listing in WordPerfect format for drawers 1-9 this segment, sorted both by folder number (original order) and chronologically.

Subject File processing (January-June, 1996)Under the direction of William Maher and Wanda Finney, graduate assistants Karen Hansen and Thomas Kmetz began processing the remainder of the subject files in January, 1996. Original folder numbers were retained. Descriptive folder titles, inclusive dates, and the date of the earliest document in each folder were assigned. The original short folder titles assigned by the Physics Department were retained on the folders, but more descriptive folder titles assigned by the University Archives were written in brackets on folders. Any unfoldered material was assigned folder numbers keyed to its original box or drawer location. These folder numbers appear in brackets on folders. (In addition, groups of folders, which, in the original Physics Department numbering scheme, were assigned only one inclusive number (for example, D-1) have been assigned their own separate sequential numbers (such as D-1-1 through D-1-13).) Earliest dates, descriptive folder titles with inclusive dates, and folder numbers were entered into a WordPerfect merge file. Dates for Subject File folders processed by Brichford were reviewed and amended as necessary to list the date of the earliest document in each folder and provide the inclusive dates of all documents in those folders. The edited text of Brichford's list for drawers 1-9 was converted to a WordPerfect merge file and combined with the first merge file.

Folders in the Subject File which contained correspondence or dissertations were separated and placed chronologically in the Correspondence or Dissertation File respectively. Folders in the Subject File with no dates or with only approximate dates were assigned an earliest date of zero. The merge file was sorted by the earliest dated document (in the format year-month-day) and by folder number thereunder. Folders in the Subject File were then arranged chronologically by date of the earliest document in each folder. Subject File material separated from material processed prior to 1991 has been coded as coming from box "Z". The subject file portion of the papers is listed on the finding aid with the three fields used in sorting the subject file: earliest date, folder number, and folder title.

Subject File Processing (October 2002)On September 27, 2002, 2.3 cubic feet of material was received from the office of Lillian Hoddeson. According to her, after the transfer of Bardeen files to archives in 1992, the secretary of the physics department informed her that papers remained in the secretary's office. These were transferred to Lillian Hoddeson's office. She subsequently deposited them in archives. These files were re-organized by existing groupings, arranged chronologically, and added to the end of the existing series as boxes 124-130. A modified finding aid was then prepared.

Subject File Processing (September 2003) On May 14, 2003, material was received from the Spurlock Museum. This material was arranged chronologically by topic and added to the end of the existing series as boxes 131-132. A modified finding aid was then prepared.

Duplicates and original folders: Duplicates (1.3 cubic feet) were separated from the papers and are being held unprocessed by the University Archives. File folders were replaced with acid-neutral folders during processing, and original folders have been retained by the Archives.