Series I contains three runs of mixed correspondence and subject files, which largely represent Stephan's own filekeeping. The first subseries, General Correspondence, consists of correspondence filed by name of individual or organization, but also includes files on subjects such as "Birds" and "Race Relations." The second subseries, Subject Files, consists of correspondence and other information filed by subject, with some unsorted correspondence at the end. The final subseries, Family Correspondence, consists of family letters and documents donated by Stephan's son in 2003. Stephan's correspondence with family members can be found in all three suberies.