The Fritz Leiber Papers contains correspondence, notes, manuscripts, typescripts, publications and tearsheets, diaries and biographical materials, financial, legal and medical records, photographs, illustrations, convention materials, and miscellaneous materials. Additional oversize art/illustration materials and ephemera such as weaponry, sculpture, and awards are housed separately. The materials date from the 1930s to the 1980s. They are housed in 60 manuscripts boxes, 5 storage boxes, and 3 oversized boxes.

The collection was compiled from 41 boxes of previously unprocessed Fritz Leiber materials, 23 boxes of Fritz Leiber papers which were processed in 1991-1992, and several boxes of letters which were donated by Franklin C. MacKnight from 1984-1991. Original provenance was lost through preliminary processing, so the order imposed on the Fritz Leiber Papers is artificial and reflects the major categories discovered during final processing. For more information, please refer to the series descriptions.