General Information About the Chicago Style of Citation

The Chicago Style works with two systems: 1) notes and bibliography, and 2) author-date. Picking one of these systems depends on your piece of writing. The notes and bibliography style is preferred when dealing with the humanities. The author-date system is associated with physical, natural, and social sciences.

Making a Reference Section in the Chicago Format

  • Label the reference section “Bibliography” when using the notes and bibliography style, and label your reference section “References” for the author-date style.
  • The reference section is the first page of the back matter.
  • Leave two blank lines between the heading and the first entry.
  • Have one blank line between all other entries.
  • List entries alphabetically according to the first word in each entry.
  • Use “and” instead of “&” for multiple-author citations.
  • When there are two to three authors, write out all the names.
  • When there are four to ten authors, write out all the names in the bibliography—but in parenthetical citations inside the text, only use the first author’s name and then “et al.”
  • When you don’t know the author of a source, show only the title on the references page and in parenthetical citations (in shortened form, with up to four keywords from that title).
  • Write out names of publishers in full.
  • Do not write access dates unless publication dates are not given.
  • If you cannot find the publication date of a printed source, use “n.d.” which means “no date.”
  • Use DOIs instead of URLs when possible.
  • When you cannot come up with a page number, you can write the section, equation, volume, or note.


One author

Bibliography and notes style:

Michael Pollan, The Omnivore’s Dilemma: A Natural History of Four Meals (New York: Penguin, 2006), 99–100.

Author-date style:

Pollan, Michael. 2006. The Omnivore’s Dilemma: A Natural History of Four Meals. New York: Penguin.

Two authors

Bibliography and notes style:

Geoffrey C. Ward and Ken Burns, The War: An Intimate History, 1941–1945 (New York: Knopf, 2007), 52.

Author-date style:

Ward, Geoffrey C., and Ken Burns. 2007. The War: An Intimate History, 1941–1945. New York: Knopf.

Creating Footnotes in the Chicago Citation Style

  • The numbers of notes should start with “1” and should continue in sequential order.
  • Within the text, note numbers are superscripted, which means it is written above the line.
  • Note numbers should be added at the end of a clause or the sentence to which they refer to.
  • Note numbers should be placed after any and all punctuation.
  • In the notes, note numbers are full-sized, not elevated like they are in the text, and followed by a period.
  • Indent the first line of a footnote .5” from the left margin.
  • The lines after the first line of a footnote should be formatted flush left.
  • Put an extra line space between footnotes.
  • Place commentary subsequent to documentation when a footnote has both, delineated by a period.
  • In parenthetical citations, separate documentation from short commentary with a semicolon.
  • Do not repeat a hundreds digit if the rest of the pages mentioned are within the same range.

General Information About the Turabian Style of Citation

The Turabian style of writing and formatting was created by Kate Turabian in order to simplify the Chicago style of citation. It is mostly used for social sciences.

The main difference between the Turabian style and the Chicago style is that Turabian is shorter and has fewer instructions. It also does not have information about publications.

After 2010 with the publication of the 16th edition of the Chicago Manual of Style, Turabian and Chicago became the same style. This is because the Turabian style was seen as authoritative, and best for students and professionals.

So, when a teacher asks you to write in the Turabian style, refer to the 16th edition of the Chicago Manual of Style.