If you have ever been told to "cite your sources" without being told how, you are not alone. APA, MLA, and Chicago are the three citation styles most universities and publishers use — and choosing the wrong one, or mixing conventions between them, is one of the most common academic writing mistakes.
This guide explains what each style is, who uses it, and shows you real formatting examples so you can apply them correctly.
Why Citation Styles Exist
Citation styles exist for two reasons: consistency and credibility. A consistent format lets readers find your sources quickly. Proper attribution signals that you have engaged with real evidence rather than asserting claims unsupported. Different academic disciplines developed different conventions because they have different priorities — scientists care about publication date, literary scholars care about page numbers, historians need to navigate archives and footnotes.
APA — American Psychological Association (7th Edition)
APA is the standard in psychology, education, nursing, social sciences, and most STEM disciplines. Its defining feature is the author-date format: citations in the body of your text show the author's last name and the year of publication. This emphasis on recency reflects scientific practice — in science, a 2024 study carries more weight than a 1994 one.
When to use APA
- Psychology, sociology, education, nursing, and public health
- Natural and social sciences (biology, economics, political science)
- Business and management research
- Any assignment where your department or journal specifies APA
APA in-text citation format
Place the author's last name and year inside parentheses at the end of the sentence: (Smith, 2023). If you name the author in the sentence, only the year goes in parentheses: Smith (2023) found that…. For direct quotes, add a page number: (Smith, 2023, p. 45).
APA reference list examples
Journal article:
Smith, J. A., & Jones, B. (2023). The effect of sleep on memory consolidation. Journal of Cognitive Psychology, 15(3), 210–225. https://doi.org/10.xxxx
Book:
Brown, C. (2021). Understanding human behaviour (3rd ed.). Oxford University Press.
Website:
World Health Organization. (2024, March 12). Mental health facts. https://www.who.int/example
Key APA quirks
- The reference list is titled "References" (not "Bibliography" or "Works Cited")
- Only the first word of an article title is capitalised (plus proper nouns)
- Journal names and volume numbers are italicised; issue numbers are not
- The 7th edition removed the "Running head" requirement for student papers
- Include a DOI wherever one exists
MLA — Modern Language Association (9th Edition)
MLA is the standard for literature, language studies, film, cultural studies, and most humanities disciplines. Its defining feature is the author-page format: in-text citations show the author's name and the page number where you found the information. This reflects the humanities priority — the exact location within a text matters when analysing language and meaning.
When to use MLA
- English literature, comparative literature, and language studies
- Film studies, media studies, and cultural theory
- History of art and visual culture
- Philosophy (sometimes — check with your department)
- Any humanities assignment where MLA is specified
MLA in-text citation format
Place the author's last name and page number in parentheses with no comma between them: (Smith 45). If you name the author in the sentence, only the page number goes in parentheses: Smith argues that memory is selective (45). No "p." before the page number.
MLA Works Cited examples
Journal article:
Smith, Jane A. "Memory and Narrative in Postwar Fiction." Modern Fiction Studies, vol. 68, no. 2, 2022, pp. 301–320.
Book:
Brown, Charles. The Language of Loss. 3rd ed., Penguin, 2019.
Website:
World Health Organization. "Mental Health Facts." WHO, 12 Mar. 2024, www.who.int/example.
Key MLA quirks
- The reference list is titled "Works Cited"
- Every major word in titles is capitalised (Title Case)
- The author's name is inverted: Last, First
- The 9th edition uses a flexible "container" system for nested sources (articles within databases, episodes within series)
- Publisher and year appear near the end, not the beginning
Chicago — Chicago Manual of Style (17th Edition)
Chicago style is used primarily in history, theology, and some arts and humanities disciplines. It has two distinct systems: Notes-Bibliography (used in history, literature, and the arts) and Author-Date (used in physical, natural, and social sciences). Most students encounter the Notes-Bibliography system.
When to use Chicago
- History — Chicago Notes-Bibliography is the standard
- Theology, religious studies, and philosophy
- Some fine arts and architecture programmes
- Publishing and journalism (author-date variant)
Chicago Notes-Bibliography format
Instead of in-text parenthetical citations, Chicago Notes-Bibliography uses footnotes or endnotes with a superscript number in the text. The full source details appear in the note the first time it is cited; shortened versions are used after that. A bibliography at the end lists all sources alphabetically.
Footnote (first citation):
¹ Jane A. Smith, The Memory of War (London: Penguin, 2021), 45.
Footnote (subsequent citation):
² Smith, Memory of War, 67.
Bibliography entry:
Smith, Jane A. The Memory of War. London: Penguin, 2021.
Key Chicago quirks
- Bibliography entries invert the first author's name; footnotes do not
- Publisher location is included (unlike APA and MLA)
- Ibid. can be used when citing the same source twice in a row (though many style guides now discourage it)
- Chicago is the most flexible of the three — it handles archival sources, manuscripts, and legal citations well
Quick Comparison
- APA: Author-date · References list · Sciences and social sciences · Recency-focused
- MLA: Author-page · Works Cited · Humanities and literature · Location-focused
- Chicago: Footnotes + bibliography · History and arts · Flexibility and archival depth
How to Choose the Right Style
In most cases, your instructor or institution will specify which style to use. If not, use discipline as your guide: sciences and social sciences → APA; literature and humanities → MLA; history and theology → Chicago.
When in doubt, pick one style and apply it consistently throughout your paper. Mixed citations — using APA format for some sources and MLA for others — are penalised more harshly than minor formatting errors within a single style.
Consistency matters more than perfection. A paper that uses APA slightly imperfectly is far better than a paper that switches between styles halfway through.
Generate Citations Instantly
Formatting citations by hand is error-prone and time-consuming. Credify's Citation Generator formats APA 7th, MLA 9th, and Chicago 17th citations from a URL or manual entry — free, no signup required.