You’ve written a strong paragraph synthesizing multiple sources, but now you need to insert in-text citations. Should it be (Smith, 2023), (Smith 45), or something else entirely? One wrong punctuation mark could confuse your reader and cost you points.

In-text citations are the backbone of academic attribution. APA, MLA, and Chicago each use a distinct system, and knowing the differences is essential for writing across disciplines. This guide provides a side-by-side comparison of all three styles with examples for every common scenario.

APA 7th Edition: Author-Date System

APA uses the author-date system, prioritizing the publication year to emphasize the currency of research. This system is standard in psychology, education, and the social sciences.

Basic Formats

Scenario	Format	Example
Parenthetical	(Author, Year)	(Smith, 2023)
Narrative	Author (Year)	Smith (2023) found that...
Direct quote	(Author, Year, p. Page)	(Smith, 2023, p. 45)
Two authors	(Author & Author, Year)	(Smith & Jones, 2023)
Three+ authors	(Author et al., Year)	(Smith et al., 2023)
Multiple sources	Alphabetical, semicolons	(Brown, 2022; Smith, 2023)

MLA 9th Edition: Author-Page System

MLA uses the author-page system, emphasizing the specific location of the cited material. This system is standard in literature, languages, and the humanities.

Basic Formats

Scenario	Format	Example
Parenthetical	(Author Page)	(Smith 45)
Narrative	Author mentions page in parens	Smith argues that... (45)
Two authors	(Author and Author Page)	(Smith and Jones 45)
Three+ authors	(Author et al. Page)	(Smith et al. 45)
No page numbers	(Author) or author in text	(Smith)

Note that MLA uses no comma between the author name and the page number, and the page number is not preceded by “p.”

Chicago Style: Two Systems

Chicago offers two documentation systems. Your discipline determines which one to use.

Notes-Bibliography (Humanities)

Sources are cited in numbered footnotes or endnotes. A superscript number in the text corresponds to a note containing the citation details.

Example: Smith argues that academic integrity is foundational to scholarly work.¹

Footnote: 1. John Smith, The Ethics of Research (Chicago: University of Chicago Press, 2024), 45.

Author-Date (Sciences & Social Sciences)

Similar to APA but with different punctuation. No comma between author and year.

Example: (Smith 2024, 45)

Key Differences at a Glance

Feature	APA 7th	MLA 9th	Chicago (Author-Date)
Citation content	Author, Year	Author, Page	Author, Year, Page
Comma after author	Yes	No	No
Page prefix	“p.” or “pp.”	None	None (Author-Date) or footnote
& vs. and	& in parentheses, “and” in narrative	“and” always	“and” always

Common In-Text Citation Mistakes

• Omitting the year in APA — Every APA in-text citation must include the year, even on repeat citations in the same paragraph.
• Adding a comma in MLA — MLA uses no comma between the author name and page number: (Smith 45), not (Smith, 45).
• Using the wrong “et al.” threshold — APA uses “et al.” for 3+ authors from the first citation. MLA uses “et al.” for 3+ authors but names all authors in the first citation.
• Mixing Chicago systems — Do not mix Notes-Bibliography with Author-Date. Pick one system and use it consistently.
• Forgetting the page number for direct quotes in APA — APA requires a page number (or other locator) for every direct quotation.

Perfect Your In-Text Citations with Formatly

Keeping track of which style uses a comma, which uses “p.,” and which uses “et al.” from the first citation is exhausting when you’re focused on writing. Formatly applies the correct in-text citation formatting for APA, MLA, Chicago, Harvard, and Turabian automatically. Upload your document and format your citations in seconds.