APA vs MLA vs Chicago: Which Citation Style Should You Use?

Three citation styles dominate Anglophone academia: APA, MLA, and Chicago. They cite the same kinds of sources — books, journal articles, websites, films — but they format every single element differently. Author name first or last? Year in parentheses or at the end? Italicize the title or the journal? Each style has an answer, and the answers don't agree.

This guide explains why each style picked the conventions it did, when to use which, and how the same source looks in all three formats so you can spot the visual difference at a glance.

Which style does your field use?

• APA (American Psychological Association): psychology, education, nursing, business, most social sciences, and a growing share of STEM fields outside biology and physics.
• MLA (Modern Language Association): English literature, foreign languages, comparative literature, philosophy, and most humanities outside history.
• Chicago / Turabian: history, art history, theology, anthropology, and many area-studies fields. Also used by most US trade book publishers.

Engineering and biomedicine often use IEEE and Vancouver respectively, which have their own logic. If your professor said "use the standard style" without naming one, default to APA in the social sciences, MLA in literature courses, and Chicago in history.

Why three styles exist (and why each chose what it did)

The differences aren't arbitrary — each style optimizes for what its field actually needs:

• APA prioritizes recency. In psychology and education, a 2003 study and a 2023 study can disagree, and the date matters as much as the author. So APA puts the year prominently right after the author's name in the in-text citation: (Kahneman, 2011).
• MLA prioritizes the page. Literary scholars argue about specific passages, so MLA puts page numbers in every in-text citation and downplays the year (literature doesn't "go out of date" the same way psychology research does): (Kahneman 47).
• Chicago prioritizes the source itself. Historians often cite archival material, primary sources, and obscure documents, so Chicago's footnote system gives space for full bibliographic detail right at the bottom of the page where the citation appears.

APA 7th edition — the basics

APA's seventh edition (released 2019, replacing the 6th edition's 2010 conventions) simplified several rules. The current shape:

In-text citation: (Author, Year, p. X) — page number only when quoting directly.

Reference list (alphabetical by author surname):

• Book:
  Kahneman, D. (2011). Thinking, fast and slow. Farrar, Straus and Giroux.
• Journal article:
  Tversky, A., & Kahneman, D. (1974). Judgment under uncertainty: Heuristics and biases. Science, 185(4157), 1124–1131. https://doi.org/10.1126/science.185.4157.1124
• Website:
  World Health Organization. (2023, March 14). Mental health and COVID-19. https://www.who.int/news/item/14-03-2023

Notable APA 7 changes from APA 6: only the first author's name is followed by "et al." starting from three or more authors (used to be six); publisher location is no longer required for books; up to 20 authors can be listed before truncation.

MLA 9th edition — the basics

MLA's ninth edition (released 2021) keeps the "container" model introduced in MLA 8 — every source is described as a work inside a container (a book, a journal, a database, a website). The current shape:

In-text citation: (Author Page) — no comma between them. (Kahneman 47).

Works Cited (alphabetical by author surname):

• Book:
  Kahneman, Daniel. Thinking, Fast and Slow. Farrar, Straus and Giroux, 2011.
• Journal article:
  Tversky, Amos, and Daniel Kahneman. "Judgment under Uncertainty: Heuristics and Biases." Science, vol. 185, no. 4157, 1974, pp. 1124–31.
• Website:
  World Health Organization. "Mental Health and COVID-19." WHO, 14 Mar. 2023, www.who.int/news/item/14-03-2023.

MLA spells first names in full (APA uses initials) and capitalizes every major word in titles (APA only capitalizes the first word and proper nouns). It also keeps the "URL without https://" convention that other styles abandoned.

Chicago — two systems in one style

Chicago is unique because it offers two completely different citation systems and you have to pick one:

• Notes-Bibliography (NB): Footnotes or endnotes for citations, plus a bibliography. Used in history, art history, literature, and most humanities work that ends up in book form.
• Author-Date: In-text parenthetical citations (similar to APA) plus a reference list. Used in physical, natural, and some social sciences when they choose Chicago over APA.

Chicago Notes-Bibliography

Footnote:

1. Daniel Kahneman, Thinking, Fast and Slow (New York: Farrar, Straus and Giroux, 2011), 47.

Bibliography entry:

Kahneman, Daniel. Thinking, Fast and Slow. New York: Farrar, Straus and Giroux, 2011.

The footnote and bibliography differ in tiny but consistent ways: the footnote uses commas and parentheses around the publication info; the bibliography uses periods and no parentheses. The footnote starts with first-name-first; the bibliography starts with surname-first.

Chicago Author-Date

In-text: (Kahneman 2011, 47).

Reference list: Kahneman, Daniel. 2011. Thinking, Fast and Slow. New York: Farrar, Straus and Giroux.

Author-date Chicago looks almost like APA but with the year separated from the author's name by a space rather than a comma — and capitalized in title case rather than sentence case. The differences are small but distinctive enough that an experienced grader spots APA-pretending-to-be-Chicago instantly.

The same book in all three styles

Daniel Kahneman's Thinking, Fast and Slow as it appears in each style's reference list:

• APA: Kahneman, D. (2011). Thinking, fast and slow. Farrar, Straus and Giroux.
• MLA: Kahneman, Daniel. Thinking, Fast and Slow. Farrar, Straus and Giroux, 2011.
• Chicago (NB): Kahneman, Daniel. Thinking, Fast and Slow. New York: Farrar, Straus and Giroux, 2011.

Differences in one line: APA uses initial + sentence-case + year-in-parens-after-author; MLA uses full name + title case + year-at-end; Chicago adds publisher city before publisher name.

Mistakes that lose points (or lose credibility)

• Mixing styles within one paper. The most common grading deduction. If you copy a citation from a Google Scholar export, check that it matches your assigned style before pasting.
• Wrong edition. APA 6 and APA 7 differ enough that a paper formatted in APA 6 in 2026 looks dated. Same for MLA 8 vs. 9.
• Hallucinated DOIs. AI-assisted writing has flooded papers with plausible-looking DOIs that 404. Every DOI should resolve at https://doi.org/{DOI} before submission.
• Wrong italics. APA italicizes book titles and journal names but not article titles. MLA does the same. Chicago italicizes book titles in both notes and bibliography. Italicizing article titles within a journal is wrong in all three.
• Missing hanging indents. All three styles require the second and subsequent lines of each reference to be indented. Word's "Hanging indent" formatting is the fix.

Generating citations correctly

Hand-formatting citations for a 50-source bibliography is tedious and error-prone. A citation generator outputs APA, MLA, and Chicago directly from a book title, ISBN, DOI, or URL — with the punctuation, italics, and capitalization all correct.

Two caveats: always proofread the output (especially the capitalization, which generators sometimes get wrong on subtitles), and remember that a generator can't tell you which style your professor wants — that's still your call.

Related guides for academic writing

Citations are one piece of the academic writing puzzle. Two others worth getting right:

• Ideal word count for essays — page-to-word conversions and how strict professors actually are about page targets.
• Percentage to GPA conversion — what your transcript GPA looks like on the US 4.0 scale that most graduate applications expect.

A two-step rule

First step: confirm your assigned style and edition before you start writing — building a bibliography in MLA 9 only to convert it to APA 7 the night before submission is one of academic writing's least rewarding experiences. Second step: use a generator for the 80% of straightforward citations and proofread the 20% that are weird (edited volumes, government reports, datasets, social media posts). The hours you save belong to the actual argument of your paper.