How to Cite Sources in MLA and APA Style: A Beginner's Guide

Citing sources can feel like a chore of commas, italics, and rules that seem to exist only to cost you marks. But citation does real work. It gives credit to the people whose ideas you used, shows your reader that your claims rest on evidence, and lets anyone follow your trail back to the original source. It also protects you from plagiarism.

This guide covers the two citation styles students meet most often: MLA (9th edition), common in English and the humanities, and APA (7th edition), common in psychology, education, and the social sciences. You’ll learn when to cite, how the two-part citation system works, and how to format the most common source types.

Always follow your instructor’s or institution’s requirements first. They may specify a particular edition or local variations. For full details, consult the official MLA Handbook and APA Publication Manual, or a trusted guide such as the Purdue Online Writing Lab.

When Do You Need to Cite?

Cite a source whenever you use:

A direct quotation: someone else’s exact words
A paraphrase: someone else’s idea, rewritten in your own words
A summary: a condensed version of someone else’s argument
Specific facts, statistics, or data that are not common knowledge
Images, charts, or tables created by someone else

You generally don’t need to cite:

Common knowledge: facts widely known and easily found in many general sources (e.g. “Paris is the capital of France” or “World War II ended in 1945”)
Your own original ideas, analysis, and conclusions

When in doubt, cite. Over-citing is a minor style issue; under-citing can be treated as plagiarism.

How Citation Works: Two Parts

Both MLA and APA use a two-part system:

In-text citations: brief references in the body of your essay, pointing to a source
A list of full references at the end: called Works Cited in MLA and References in APA

Each in-text citation must match an entry in the list, and each entry in the list must be cited at least once in the text.

MLA Style (9th Edition)

MLA emphasizes authors and page numbers, reflecting the humanities’ focus on close reading of texts.

MLA in-text citations

Use the author’s last name and the page number, with no comma between them:

Early start times have been linked to lower attendance (Rivera 42).

If you name the author in your sentence, only the page number goes in parentheses:

Rivera argues that early start times reduce attendance (42).

Two authors: (Rivera and Chen 42)
Three or more authors: (Rivera et al. 42)
No page numbers (e.g. websites): just the author (Rivera)
No author: use a shortened title in quotation marks or italics (“Sleep and Learning”)

MLA Works Cited entries

MLA 9 builds every 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, Location.

The examples below use fictional sources for illustration.

Book:

Rivera, Ana. The Rested Mind: Sleep and Learning in Adolescence. Northfield Press, 2021.

Journal article:

Chen, Wei, and Laura Okafor. “School Start Times and Student Attendance.” Journal of Education Research, vol. 34, no. 2, 2022, pp. 115–31. https://doi.org/10.0000/example.2022.

Web page:

Patel, Sam. “Why Teenagers Can’t Fall Asleep Early.” Healthy Schools Network, 14 Mar. 2023, www.example.org/teen-sleep.

MLA formatting tips

Title the page Works Cited, centered.
List entries alphabetically by the author’s last name.
Use a hanging indent (second and later lines indented 0.5 inch).
Double-space the whole list.
Italicize titles of whole works (books, journals, websites); put titles of parts (articles, chapters, web pages) in “quotation marks.”
Use title case for titles (capitalize major words).

APA Style (7th Edition)

APA emphasizes authors and dates, reflecting the sciences’ concern with how recent research is.

APA in-text citations

Use the author’s last name and the year, separated by a comma:

Early start times have been linked to lower attendance (Rivera, 2021).

For direct quotations, add the page number:

Rivera (2021) described early start times as “a mismatch between school and biology” (p. 42).

Two authors: (Chen & Okafor, 2022). Use ”&” in parentheses and “and” in running text.
Three or more authors: (Smith et al., 2020) from the first citation
No author: use the first few words of the title and the year
No date: use “n.d.” (Patel, n.d.)

APA reference list entries

The examples below use fictional sources for illustration.

Book:

Rivera, A. (2021). The rested mind: Sleep and learning in adolescence. Northfield Press.

Journal article:

Chen, W., & Okafor, L. (2022). School start times and student attendance. Journal of Education Research, 34(2), 115–131. https://doi.org/10.0000/example.2022

Web page:

Patel, S. (2023, March 14). Why teenagers can’t fall asleep early. Healthy Schools Network. https://www.example.org/teen-sleep

APA formatting tips

Title the page References, bold and centered.
List entries alphabetically by the first author’s last name.
Use a hanging indent and double-spacing.
Use initials for authors’ first and middle names.
Use sentence case for article and book titles (capitalize only the first word, the first word after a colon, and proper nouns).
Italicize book titles, journal names, and journal volume numbers.
Present DOIs as full URLs (https://doi.org/…).

MLA vs. APA at a Glance

	MLA (9th ed.)	APA (7th ed.)
Common in	English, languages, humanities	Psychology, education, social sciences
In-text format	(Author page)	(Author, Year)
Example	(Rivera 42)	(Rivera, 2021)
Two authors	(Rivera and Chen 42)	(Rivera & Chen, 2021)
List title	Works Cited	References
Author names	Full first name	Initials
Title capitalization	Title Case	Sentence case
Date position	Near the end	Right after the author

Quoting, Paraphrasing, and Summarizing

All three require a citation, but they work differently.

Quoting uses the author’s exact words in quotation marks. Use quotations sparingly, when the exact wording matters, such as a memorable phrase, a definition, or a passage you’re analyzing.

Paraphrasing restates a specific idea in your own words and sentence structure. Changing a few words is not enough; that’s called “patchwriting” and may still count as plagiarism.

Original: “Adolescents experience a biological shift in their sleep cycle that makes it difficult to fall asleep before 11 p.m.”

Patchwriting (too close): Teenagers have a biological change in their sleep cycle that makes it hard to go to sleep before 11 p.m.

Good paraphrase: Because the body’s internal clock moves later during the teenage years, most adolescents physically struggle to fall asleep until late at night (Rivera, 2021).

Summarizing condenses a longer passage or a whole source into a few sentences, capturing only the main idea.

Avoiding Plagiarism

Plagiarism means presenting someone else’s words or ideas as your own, intentionally or not. To avoid it:

Take careful notes. When researching, mark quotations clearly and always record the source. Most accidental plagiarism starts with messy notes.
Paraphrase from understanding. Read the passage, close the source, write the idea in your own words, then check back for accuracy.
Cite as you write. Don’t plan to “add citations later,” because you’ll forget where ideas came from.
Use quotation marks for any distinctive phrase you borrow, even a short one.
Check your institution’s policy on AI tools and on reusing your own previous work.

Tools That Can Help

Citation generators (including those built into word processors and library databases) can save time, but they often make mistakes with capitalization, missing information, and formatting. Always check generated citations against a reliable guide before submitting.

Practice Exercise

Using the fictional details below, write the source in both MLA and APA format, plus one in-text citation in each style:

Author: Daniel Moreau
Title: Speaking Without Fear
Publisher: Harbor Books
Year: 2020
You’re quoting page 88.

Answers:

MLA: Moreau, Daniel. Speaking Without Fear. Harbor Books, 2020. In-text: (Moreau 88)
APA: Moreau, D. (2020). Speaking without fear. Harbor Books. In-text: (Moreau, 2020, p. 88)

Getting citations right is part of building credibility in your writing. To learn how to turn your sources into a strong argument, see our guide on writing an argumentative essay.