Citation

APA vs MLA vs Chicago vs Harvard

Q: Which citation style should I use?

Follow your assignment brief first. By discipline: APA for social sciences, education, nursing and business; MLA for English and the humanities; Chicago for history, the arts and publishing; Harvard is common in the UK and Australia.

Four common styles, four sets of rules. Here’s what each is for, how they differ, and the same source written in each.

Why citation styles exist

Citing sources does three jobs: it gives credit to the people whose ideas you used, it lets readers find those sources, and it protects you from plagiarism. Different fields adopted different styles, but they all carry the same core information — author, date, title and where to find it — in a different order.

The main styles at a glance
Style	Typical fields	In-text	List is called	Current edition
APA	Social sciences, nursing, business	(Author, Year)	References	7th (2020)
MLA	English, humanities	(Author 23)	Works Cited	9th (2021)
Chicago (notes)	History, arts, publishing	Footnote¹	Bibliography	18th (2024)
Harvard	UK / Australia, many fields	(Author Year)	Reference list	No single manual

The same book in three styles

Using an illustrative book — The Origins of Language by Jordan Smith, published by Aldridge Press in 2020:

APA 7

Smith, J. (2020). The origins of language. Aldridge Press.

In-text: (Smith, 2020)

MLA 9

Smith, Jordan. The Origins of Language. Aldridge Press, 2020.

In-text: (Smith 14)

Chicago 18 (notes-bibliography)

Smith, Jordan. The Origins of Language. Chicago: Aldridge Press, 2020.

Note: 1. Jordan Smith, The Origins of Language (Chicago: Aldridge Press, 2020), 14.

How to choose

Check the assignment brief or syllabus first — it almost always names a style. If it doesn’t, use the discipline norm in the table above. Then be consistent from the first citation to the last.

Frequently asked questions

Which citation style should I use?

Follow your assignment brief first. By discipline: APA for social sciences, education, nursing and business; MLA for English and the humanities; Chicago for history, the arts and publishing; Harvard is common in the UK and Australia.

Can I mix two styles in one paper?

No. Pick one and use it consistently — mixing styles is one of the most common reasons work gets marked down.

Is Chicago 17th still acceptable?

Chicago’s 18th edition (2024) is current, but many courses and journals still use the 17th. Use whichever your instructor or publisher specifies.

How do I cite AI tools like ChatGPT?

APA 7, MLA 9 and Chicago 18 all now give guidance for AI-generated content: name the tool as the source, give the version and date, and say how you used it. Always check your school’s own policy first.

These guides explain the current editions in plain language and are a study aid, not official style manuals. For exact rules and edge cases, check your assignment brief and the official APA, MLA or Chicago guidance — and when in doubt, ask your instructor.