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

Why Citation Styles Exist

Academic citation styles exist because different fields of scholarship have different priorities. Scientists need readers to be able to verify the currency of a source quickly — so they put the year right after the author name. Humanities scholars care more about the precise location in a text (page numbers matter when you're discussing a novel's wording) — so they embed page numbers in in-text citations. Legal scholars need exhaustive footnotes to trace the precedent chain — so they use a footnote-heavy system.

The three most widely used styles in academic writing are:

• APA (American Psychological Association) — author-date, science-oriented
• MLA (Modern Language Association) — author-page, humanities-oriented
• Chicago (University of Chicago Press) — flexible, two systems, covers history and publishing

Understanding which style to use — and why — makes you a more informed and adaptable academic writer.

APA Style: Overview

APA style was developed by the American Psychological Association and is now in its 7th edition (2020). It is the standard in psychology, education, nursing, social work, sociology, communication, and many health sciences.

Core mechanism: Author-date in-text citations — (Author, Year) or (Author, Year, p. X). Full reference at the end in a "References" list.

What APA emphasises:

• The recency of research — year is prominent in both in-text citations and the reference list
• Precise attribution — page numbers are required for direct quotations
• Accessibility of digital sources — DOIs and URLs are standard components
• Gender-neutral language and bias-free writing (APA 7 expanded these guidelines significantly)

APA references are listed alphabetically by author in a page titled "References" (not "Bibliography" or "Works Cited").

MLA Style: Overview

MLA style was developed by the Modern Language Association and is now in its 9th edition (2021). It is used primarily in English literature, cultural studies, comparative literature, foreign languages, linguistics, and other humanities disciplines.

Core mechanism: Author-page in-text citations — (Author Page). Full citation in a "Works Cited" list.

What MLA emphasises:

• Location within a text — page numbers appear in every in-text citation (not just quotations)
• Flexibility — the "container" system allows MLA to handle any source type with a single universal framework
• Simplicity in in-text form — the in-text citation is as brief as possible

Works Cited is always the final page of an MLA paper, alphabetised by author surname.

Chicago Style: Overview

Chicago style comes from the Chicago Manual of Style, now in its 17th edition (2017). It is used widely in history, the arts, philosophy, religious studies, and in professional publishing. Unusually, Chicago offers two systems:

• Notes-Bibliography (NB): Footnotes or endnotes with full source information, plus a bibliography at the end. Preferred in humanities (especially history, literature, art history).
• Author-Date (AD): Parenthetical in-text citations like APA, with a "References" list. Preferred in social sciences and sciences when using Chicago style.

Most students using Chicago style will use the Notes-Bibliography system unless told otherwise.

Which Disciplines Use Which Style

Note that conventions vary by university, department, and even individual professor. The table above reflects common practices, not absolute rules. Always follow your specific course guidelines.

In-Text Citation Comparison

Using a consistent example: the same psychology journal article by Brown and Patel (2023), page 517, containing a direct quotation.

APA 7

Or: "Passive consumption was more harmful (Brown & Patel, 2023, p. 517)."
Note: Ampersand (&) inside parentheses; "and" spelled out in prose.

MLA 9

Note: No year in the in-text citation. Page number only. No "p." before the number.

Chicago (Notes-Bibliography)

The superscript number corresponds to a footnote or endnote — no parenthetical citation appears in the text itself.

Reference Entry Comparison

The same journal article: Brown, K.L., & Patel, S. (2023). "Social media use and adolescent well-being: A meta-analysis." Journal of Adolescent Health, 72(4), 512–524. DOI: 10.1016/j.jadohealth.2022.11.003

Website Citation Comparison

Citing: World Health Organization, "Obesity and overweight fact sheet," updated March 2024, accessed April 2024. https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight

APA 7:

MLA 9:

Chicago (Notes-Bibliography):

Key Formatting Differences at a Glance

APA vs Harvard — Common Student Confusion

Many students confuse APA and Harvard because both are author-date systems. The differences are important:

• APA is a formally published, actively maintained style guide (7th edition, 2020) with explicit rules for every situation. It is most common in North America.
• Harvard is not a single official style. It is a family of author-date conventions used mainly in the UK, Australia, and New Zealand. Different institutions have slightly different Harvard variants. There is no single "Harvard Manual."
• Key practical difference: In APA 7, the DOI is formatted as https://doi.org/10.xxx. In many Harvard guides, it is formatted as doi: 10.xxx.
• In APA, the publication date always goes in parentheses immediately after the author. In some Harvard variants, the date goes after the author but outside parentheses, or uses slightly different formatting of author initials.

If your assignment says "Harvard style," ask your tutor or check your institution's official Harvard referencing guide — do not assume it is identical to APA.

Can You Mix Citation Styles?

No. Consistency is non-negotiable in academic writing. Every source in a paper must be cited in the same style, and every in-text citation must correspond to a correctly formatted entry in the reference list (or footnotes). Mixing APA and MLA formatting, or switching between styles within a paper, is considered a formatting error and will typically result in a grade penalty.

If you're working on a multi-chapter thesis where different chapters were originally written in different styles, you must standardise all citations to a single style before submission.

How to Know Which Style Your Professor Wants

• Check the assignment brief first. Most assignment instructions specify the required citation style explicitly.
• Check your course syllabus. Department-wide or course-wide style requirements are often stated at the start of a module.
• Check your department's guidelines. Many departments publish a style guide on their website.
• Look at the journal your professor assigned. If you're writing a mock journal submission, the assigned journal's style is often a strong hint.
• Ask. If none of the above gives a clear answer, emailing your professor or teaching assistant is always acceptable. It's a better outcome than submitting in the wrong style.

Use Bibloq to Switch Formats Instantly

Once you've confirmed which style your paper requires, Bibloq makes formatting every citation straightforward. Paste a URL, DOI, ISBN, or enter source details manually. Select APA 7, MLA 9, Chicago, Harvard, or any of 18 additional formats. Bibloq generates the correctly formatted citation in seconds. You can also switch the format for any saved source with a single click — no manual reformatting required.