Citations & References

Citation Style Guide: APA, MLA, Chicago, and Harvard Compared

Four major citation styles, used in different fields, with subtly different rules. Here's the practical comparison — what each looks like, when to use which, and the tools that handle most of the formatting for you.

Emily Walsh
By 3 min read
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On this page 9 sections
  1. 1 The four major styles, at a glance
  2. 2 APA (American Psychological Association)
  3. 3 MLA (Modern Language Association)
  4. 4 Chicago (Chicago Manual of Style)
  5. 5 Harvard
  6. 6 Which to use: the practical answer
  7. 7 Tools that handle most of the work
  8. 8 The 5 citation mistakes that cost marks
  9. 9 One habit that helps most
An academic style guide on a study desk with reference books

Four major citation styles, used in different fields, with subtly different rules. Here's the practical comparison — what each looks like, when each is appropriate, and the tools that handle most of the formatting work automatically.

The four major styles, at a glance

Style Used in In-text format
APA Psychology, Education, Social Sciences (Smith, 2024)
MLA Humanities, Literature, Languages (Smith 47)
Chicago History, Some Sciences (varies) Footnote OR (Smith 2024, 47)
Harvard Many UK/Australian universities (broad) (Smith 2024, p.47)

APA (American Psychological Association)

In-text: Author-date. (Smith, 2024) for paraphrase; (Smith, 2024, p. 47) for direct quote.

Reference list: Alphabetical by author surname.

Distinguishing features: Author's first name as initials only. Year prominently placed. Book titles in italic title case; article titles in plain sentence case.

Use it if: You're in psychology, education, or most social sciences. Or if your supervisor specifies APA.

MLA (Modern Language Association)

In-text: Author-page. (Smith 47) — note: no comma, no year.

Works Cited: Alphabetical by author surname.

Distinguishing features: Page numbers prominent in citations. Authors' full first names spelled out. Strong emphasis on locating exactly where in a source a claim came from.

Use it if: You're in literature, languages, humanities. Or if your discipline cares about page-level citation precision (literary analysis especially).

Chicago (Chicago Manual of Style)

Two systems exist:

  • Notes-Bibliography: Footnotes for each citation, plus a bibliography at the end. Used in history, art history, much of the humanities.
  • Author-Date: In-text (Smith 2024, 47) format, plus a reference list. Used in some sciences and social sciences.

Distinguishing features: The notes-bibliography system is the most intricate of the four. First citation includes full bibliographic info; later citations are abbreviated.

Use it if: You're in history, classics, religious studies, art history. Or if your supervisor specifies Chicago.

Harvard

In-text: Author-date with comma. (Smith, 2024) or (Smith, 2024, p. 47).

Reference list: Alphabetical by author surname.

Distinguishing features: Looks similar to APA but has its own punctuation conventions. The catch with Harvard is that it varies between institutions — your university may have its own specific Harvard variant.

Use it if: You're at a UK or Australian university and your discipline uses Harvard. Or if your supervisor specifies Harvard.

Which to use: the practical answer

You don't pick. Your discipline (or your supervisor) does. The decision tree:

  1. Check your dissertation handbook. The required style is specified.
  2. If it's not, ask your supervisor directly.
  3. If they say "use whatever's standard," default to: APA for sciences, MLA for humanities, Chicago for history.
  4. If you're at a UK/Australian university, check whether your school uses Harvard.

Pick before you start writing. Switching styles mid-dissertation is painful and error-prone.

Tools that handle most of the work

Stop formatting citations manually. The tools below handle 90% of the work automatically.

  • Zotero (free) — the gold standard for academic citation management. Captures sources from any browser, formats in any style, integrates with Word and Google Docs.
  • Mendeley (free, owned by Elsevier) — similar to Zotero. Slightly more PDF-management focused. Either is fine.
  • EndNote (paid, often through your university) — heavyweight option. Most universities provide free access to students.
  • Citation Machine, Cite This For Me — fine for one-off citations but unsuitable for full dissertations.

Pick one tool. Set it up properly in your first week. Use it for every citation. Don't handcraft citations during writing — you'll inevitably make formatting mistakes that will cost you marks at submission.

The 5 citation mistakes that cost marks

  1. Inconsistent style. Half APA, half MLA. Examiner notices immediately.
  2. Missing page numbers for direct quotes. APA, Chicago, Harvard all require this.
  3. Sources cited in-text but missing from references. Or vice versa. Both are scored as errors.
  4. Mis-formatted titles. Italic vs quotes vs plain. Specific to each style.
  5. Inconsistent date formats. 2024 vs (2024) vs 2024a vs 2024, p.47. Each style has rules; follow them.

One habit that helps most

Add every source to Zotero (or your tool of choice) BEFORE you cite it in your draft. The 30 seconds at the front of the process saves hours of formatting work at the back. Every working academic I know does this. Most stuck dissertation writers I work with do not.