APA vs. Chicago: differences and when to use each

APA vs. Chicago: which Chicago?

Before you compare anything, ask which Chicago. The manual contains two systems:

Chicago author-date looks a lot like APA. Both use parenthetical author-year citations and end with a reference list. Chicago notes-bibliography is a different beast. Footnotes in the text, a bibliography at the end. We'll walk through both.

APA vs. Chicago author-date

These are the two big author-date systems in academic publishing. They look almost identical at a glance. The differences live in a few small conventions.

Three differences jump out:

1. Author names. APA uses initials only ("Sampson, R. J."). Chicago spells out the full first name ("Sampson, Robert J.").

2. Year placement and punctuation. APA puts the year in parentheses with a period: "(2012)." Chicago places the year directly after the author with a period: "2012."

3. Title capitalization. APA is sentence case. Chicago is headline case for book titles.

APA vs. Chicago notes-bibliography

This comparison is a different conversation. Two different philosophies of citation. APA drops the citation right into the sentence. Chicago NB sends it to the bottom of the page.

APA's parenthetical is quick to scan, but you can't pack much around it. A Chicago footnote has room. It can hold a translation, a hedge, an extra quotation, all alongside the source. That's why historians stick with it.

Which to use when

Reference list vs. bibliography

APA and Chicago author-date both finish with an alphabetized list under the heading References. Chicago NB papers end with a Bibliography. One important quirk: a Chicago bibliography can include sources you consulted but didn't cite. APA doesn't allow that.

Title capitalization and author names

APA is sentence case throughout. Chicago uses headline case for book and journal article titles, in both AD and NB.

APA uses initials for first names. Chicago spells them out when the source does. That's the fastest way to tell the two styles apart at a glance.

DOIs and URLs

APA 7 requires DOIs as full URLs (https://doi.org/10.xxxx/yyyy) with no trailing period. Chicago accepts the same form. Both styles have dropped the older doi:10.xxxx/yyyy shortcut. Chicago NB places the DOI at the very end of the note or bibliography entry, with a comma right before it. APA leaves it on its own with no terminal punctuation.

Common mistakes when switching

Comma between author and year

APA puts a comma there: (Sampson, 2012). Chicago author-date doesn't: (Sampson 2012). Carrying the APA comma over into a Chicago paper is the conversion error we see most.

Sentence case in Chicago

Chicago uses headline case for both books and journal articles. Dragging APA's sentence case into a Chicago reformat is an easy slip.

Wrong list heading

APA goes to References. Chicago AD goes to References. Chicago NB goes to Bibliography. Labeling a Chicago NB list "References" is a giveaway that the styles got mixed.

Summary