Chicago (18th ed.) Citation Style Guide: Paper Format/Guidelines

Chicago Style has two referencing style systems – the Notes/Bibliography style system (also known as 'Humanities style') and the Author/Date style system (also known as 'Scientific/Social Sciences style'). The Author-Date method uses in-text parenthetical references and a reference list. 

This guide covers the Notes/Bibliography style system, which uses notes (either footnotes or endnotes) and a bibliography at the end of the paper.  

General guidance

• Double space the main body of the essay. 
• Entries in the bibliography and endnotes are single spaced within entries, but double spaced between entries (unless your instructor prefers double-spacing throughout).
• Footnote form and bibliographic form differ slightly. Each entry provides an example of an entry's bibliographic form and footnote form. In bibliographic entries, the second and all subsequent lines should be indented in a "hanging indent" fashion. In notes, the first line is indented.
• When no date is provided, the abbreviation n.d. takes the place of the year in the publication details (Chicago Manual of Style, 18th ed., 14.44).

Notes

• Notes can be either footnotes (placed at the bottom of the same page as the referenced text) or endnotes (listed on a separate sheet at the end of the essay). Footnotes and endnotes are structured in exactly the same way. The line spacing of notes should match the line spacing in the rest of the document (Chicago Manual of Style, 18th ed., 2.26)
• When citing a source, insert a superscript (raised) number within the text. Use normal full sized font numbers for note reference numbers in the notes themselves. The notes are numbered consecutively throughout the paper. Most word processing programs handle footnotes automatically (Chicago Manual of Style, 18th ed., 13.27-29).
• If the bibliography includes all works cited in the notes, a shortened form can be used in the notes (Chicago Manual of Style, 18th ed., 13.18).

Bibliography

• The bibliography is given on a separate page at the end of a paper (or a chapter of a multiauthor book). 
• The entries are organized alphabetically by the author's last name or by the title if the item's author is anonymous (Chicago Manual of Style, 18th ed., 13.66). 
• For works with more than six authors, list only the first three in the bibliography, followed by et al. (in the notes, only the first would be listed) (Chicago Manual of Style, 18th ed., 13.78).

- Location will no longer be required in citations and bibliography entries

• 13.23, 13.107. Up to six authors are now listed in a bibliography or reference list entry; if more than six, only the first three are listed, followed by “et al.” In a shortened note or an author-date text citation, up to two authors are now listed; if more than two, only the first is listed, followed by “et al.”
• 13.26. A month or season can now usually be omitted in citations of journal articles.
• 13.37. Shortened citations used instead of “ibid.” may take one of three forms: author-title (Chicago’s regular short form), author-only, or title-only.
• 13.47. Required elements of a citation that have been mentioned in the text can often be omitted from a footnote (because of its proximity to the text) but not usually from an endnote.
• 13.75. Authors whose names follow Eastern order (family name first) rather than Western order (family name last) are not normally inverted in a bibliography or reference list.
• 14.8. The page range for a cited chapter in an edited book is no longer required in a bibliography or reference list entry (though a page range is still required for most journal articles).
• 14.30. A place of publication is no longer required in citations of books published after 1900.
• 14.112. New guidance on citing AI-generated content.
• 14.136–37. New guidance on citing Indigenous sources.
• 14.157. Updated and expanded guidance on citing databases and datasets.