APA, MLA and Chicago are the three most widely used citation styles, and the right one usually depends on your subject. APA suits the social sciences, MLA the humanities and languages, and Chicago history and some arts subjects.
This guide compares the three side by side, so you can see exactly how the same source changes from one style to the next, and decide which one your paper needs if your instructions do not say.
The Short Answer on APA, MLA and Chicago
Use the style your instructor or department names. If there is no instruction, follow your discipline: APA for psychology, education, nursing and most social sciences; MLA for literature, languages and cultural studies; Chicago for history, art history and many humanities papers that rely on footnotes.
The biggest practical difference is the in-text citation. APA puts the year up front (Lee, 2020), MLA gives the page (Lee 45), and Chicago notes-bibliography uses numbered footnotes.
Why Different Styles Exist
Each style reflects what its disciplines value. Scientists want to know how recent the evidence is, so APA highlights the date. Literary scholars quote texts closely, so MLA highlights the page. Historians often need to comment on their sources, so Chicago gives them footnotes.
Once you see that logic, the differences stop feeling arbitrary. Each style puts the most useful information where readers in that field look first.
The Three Styles at a Glance
| APA 7 | MLA 9 | Chicago | |
|---|---|---|---|
| Main fields | Psychology, education, nursing, business, social sciences | Literature, languages, film, cultural studies | History, art history, theology, some social sciences |
| In-text system | Author-date | Author-page | Footnotes (notes-bibliography) or author-date |
| Source list title | References | Works Cited | Bibliography (or References for author-date) |
| Author names in list | Surname, initials | Surname, full first name | Surname, full first name |
| Article titles | Sentence case, no quotation marks | Title case, in quotation marks | Title case, in quotation marks |
| Date position | Straight after the author | Near the end | Near the end (notes-bibliography) |
APA Style in Brief
APA 7 is built around the date. In-text citations give the author and year, adding a page number only for direct quotations. Three or more authors are shortened to the first author and "et al." from the first citation.
In the reference list, authors appear with initials only, article and book titles use sentence case, and journal names and volume numbers are italic. APA 7 leaves out the publisher's location.
MLA Style in Brief
MLA 9 builds every Works Cited entry from a set of core elements in a fixed order: author, title of source, title of container, other contributors, version, number, publisher, publication date and location. A container is the larger work that holds the source, such as a journal, website or anthology.
In the text, MLA gives the author's surname and page number with no comma: (Morrison 112). If there is no page number, give the author alone.
Chicago Style in Brief
Chicago offers two systems. Notes-bibliography uses numbered footnotes or endnotes plus a bibliography and is standard in history and much of the humanities. Author-date works much like APA and is used in some sciences and social sciences.
The first note for a source gives full details; later notes use a shortened form with the author's surname, a short title and the page. The 17th edition is still widely taught, and the 18th edition (2024) keeps the same basic patterns.
In-Text Citations Compared
Here is the same quotation from page 45 of a single-author book, cited in each style.
APA 7: (Hassan, 2019, p. 45) or Hassan (2019) argued that "..." (p. 45).
MLA 9: (Hassan 45) or Hassan argues that "..." (45).
Chicago notes-bibliography: a superscript number in the text, with the note: 1. Amira Hassan, Cities of Water (London: Verso, 2019), 45.
Chicago author-date: (Hassan 2019, 45)
Notice the small but marked differences: APA uses a comma before the year and "p.", MLA uses no comma and no "p.", and Chicago author-date uses no comma between author and year but a comma before the page.
Reference Entries Compared
The same journal article, formatted for each style's source list.
APA 7: Kariuki, N., & Osei, D. (2021). Urban heat and public health. Environmental Research, 195(4), 210–225. https://doi.org/10.1016/j.envres.2021.110841
MLA 9: Kariuki, Njeri, and Daniel Osei. "Urban Heat and Public Health." Environmental Research, vol. 195, no. 4, 2021, pp. 210–25, https://doi.org/10.1016/j.envres.2021.110841.
Chicago bibliography: Kariuki, Njeri, and Daniel Osei. "Urban Heat and Public Health." Environmental Research 195, no. 4 (2021): 210–25. https://doi.org/10.1016/j.envres.2021.110841.
And a book with one author:
APA 7: Hassan, A. (2019). Cities of water. Verso.
MLA 9: Hassan, Amira. Cities of Water. Verso, 2019.
Chicago bibliography: Hassan, Amira. Cities of Water. London: Verso, 2019.
Chicago's 18th edition no longer requires the place of publication, so check whether your instructor expects it.
Website Citations Compared
APA 7: Lopez, M. (2023, June 12). Why bees matter. Garden Science. https://www.example.org/bees
MLA 9: Lopez, Maria. "Why Bees Matter." Garden Science, 12 June 2023, www.example.org/bees.
Chicago bibliography: Lopez, Maria. "Why Bees Matter." Garden Science. June 12, 2023. https://www.example.org/bees.
MLA allows you to leave out "https://" in URLs, while APA and Chicago keep the full address. In APA the page title is italic; in MLA and Chicago it sits in quotation marks.
Page Layout Differences
The styles differ in how the paper itself looks, not only in citations. These are the defaults; your instructor's requirements always take priority.
| Layout element | APA 7 | MLA 9 | Chicago (student papers) |
|---|---|---|---|
| Title page | Yes, separate page | No; a four-line heading at the top left of page one | Usually a separate title page |
| Header | Page number top right | Surname and page number top right | Page number, position set by your instructor |
| Spacing | Double throughout | Double throughout | Double for body text; notes and bibliography entries single-spaced with a blank line between |
| Headings | Five defined levels | No required format; keep them consistent | No fixed system; keep them consistent |
Quotations
Long quotations are set as indented blocks in all three styles, but the trigger differs. APA uses 40 words or more. MLA uses more than four lines of prose. Chicago uses about 100 words or more, while Turabian, its student version, uses five or more lines.
Numbers and Dates
APA writes most numbers 10 and above as numerals. Chicago, in humanities writing, spells out whole numbers from zero to one hundred. MLA spells out numbers that can be written in one or two words. These small habits are easy to overlook when switching styles.
APA vs Harvard: A Common Confusion
Harvard is also an author-date style, so it looks similar to APA, but it is not one fixed standard. Each university publishes its own version, and punctuation varies: some use a comma between author and year, some do not.
If your module says "Harvard", follow your university's own Harvard guide rather than APA. If it says APA, do not switch to Harvard habits such as putting the year without brackets in the reference list.
How to Know Which Style to Use
- Check the assignment brief, rubric and module handbook first.
- Look at your department's writing guidelines or library pages.
- If you are submitting to a journal, read its author guidelines.
- If nothing is specified, ask your instructor, then use the style most common in your field.
Never mix styles in one paper. Choose one and apply it consistently to every citation and entry.
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Frequently Asked Questions
The in-text system. APA uses author and year, MLA uses author and page, and Chicago notes-bibliography uses numbered footnotes. Each also formats its source list differently.
It depends on the subject. APA dominates the social sciences, health and education, MLA is common in English and humanities courses, and Chicago is standard in history.
Turabian is a student version of Chicago with the same citation patterns, adapted for papers, theses and dissertations rather than publication.
No. Use one style consistently throughout a paper, including every in-text citation and every entry in the source list.
No. MLA in-text citations give the author and page number only. The date appears in the Works Cited entry.
Chicago notes-bibliography and Turabian use footnotes or endnotes. APA and MLA use in-text citations in brackets instead.
No. Both are author-date styles, but Harvard varies between universities. Follow your institution's Harvard guide if your module asks for Harvard.
Ask. If you cannot, use the style most common in your discipline and apply it consistently.