Introduction to APA Style

When to Use APA Style

APA style, which is based on the American Psychological Association style manual, is widely used in many forms of academic writing.

Learning Objectives

Recognize when to use APA style in writing

Key Takeaways

Key Points

  • APA style is one of the most common citation and formatting styles you will encounter in your academic career.
  • APA style is based on the style guide of the American Psychological Association (APA), officially titled the Publication Manual of the American Psychological Association.
  • APA style is not used only in the field of psychology; it is extremely common throughout the social and behavioral sciences.
  • APA style provides guidelines for grammar, formatting, and citing your sources.

Key Terms

  • APA style: A common citation and formatting style, used especially often in the social and behavioral sciences.

APA style is one of the most common citation and formatting styles you will encounter in your academic career. Any piece of academic writing can use APA style, from a one-page paper to a full-length book. It is widely used by hundreds of scientific journals and many textbooks. If you are writing a paper for a psychology or sociology class, it is possible that your professor will ask you to write in APA style.

The APA Manual

APA style is based on the style guide of the American Psychological Association (APA), officially titled the Publication Manual of the American Psychological Association. But APA style is not used only in the field of psychology; in fact, it is extremely common throughout the social and behavioral sciences, and somewhat common in other scientific fields, such as medicine.

The most recent version of the APA manual is the sixth edition, second printing (which corrected errors found in the first printing), published in 2009. The sixth edition introduced guidelines for citing online sources and online-access journal articles.

The Purpose of APA Style

The APA style guide aims to accomplish several goals:​

  1. to ensure consistent formatting and presentation of information, for the sake of clarity and ease of navigation;
  2. to ensure proper attribution of ideas to their original sources, for the sake of intellectual integrity; and
  3. to provide a clear structural scaffold for an experimental paper, for the sake of scientific rigor.​

Grammar and Formatting

APA style includes many basic grammatical rules. For example, APA style does use the Oxford comma, which some other citation styles (e.g., AP style) do not. Other examples include rules about what punctuation should be included inside a quotation and when to use what type of dash.

APA style also has rules about formatting, such as how to use different levels of headers throughout your paper and what size margins you should use.


APA style also puts forth guidelines for citing your sources—in fact, this is why it is called a “citation style.” For example, APA style has specific rules for what information to include in your References section, how to cite quotations within a paragraph, and how to incorporate block quotations.

The Scientific Method

​APA style rules are not limited to grammar and formatting; in fact, it was originally developed as a set of guidelines for writing without bias in the sciences. The guidelines for reducing bias in language have been updated over the years and provide practical guidance for writing about race, ethnicity, age, gender, sexual orientation, and disability status.

APA style provides a roadmap for the structure of a scientific paper that closely mirrors the scientific method, with sections for the Introduction (including your hypothesis), Method, Results, and Discussion.

Overall Structure and Formatting of an APA Paper

Every paper written in APA style has the same basic structural elements.

Learning Objectives

Identify the structural elements of an APA paper

Key Takeaways

Key Points

  • An APA paper should include a title page, an abstract, a body, references, and in some cases, a table of contents and/or endnotes.
  • There are specific APA guidelines for font (12pt Times or Times New Roman), line spacing (double-spaced), margins (1 inch), indentation, and page numbering.
  • When writing an APA paper, be sure to use the Oxford comma, and only use one space following periods.
  • Listen to your professor’s specific guidelines if they want you to use a table of contents.

Key Terms

  • Oxford comma: The comma that comes after the second to last item in a list.

Overall Structure of an APA Paper

Your APA paper should include the following basic elements:

  1. Title page
  2. (In rare cases) Table of contents
  3. Abstract
  4. Body
  5. References
  6. (In rare cases) Endnotes

General Formatting Rules


Your paper should be written in 12-point Times or Times New Roman font.

Line Spacing

All text in your paper should be double-spaced.


All page margins (top, bottom, left, and right) should be 1 inch (or greater, but 1 inch is standard). All text, with the exception of headers, should be left-justified.


The first line of every paragraph and footnote should be indented 1 inch (with the exception of the first line of your Abstract, which should begin at the margin).

Page Numbers

Page numbers in Arabic numerals (1, 2, 3…) should appear right-justified in the header of every page, beginning with the number 1 on the title page. Most word-processing programs have the ability to automatically add the correct page number to each page so you don’t have to do this by hand.

General Grammar Rules

The Oxford Comma

The Oxford comma (also called the serial comma) is the comma that comes after the second-to-last item in a series or list. For example:

The UK includes the countries of England, Scotland, Wales, and Northern Ireland.

In the above sentence, the comma immediately after “Wales” is the Oxford comma.

In general writing conventions, whether the Oxford comma should be used is actually a point of fervent debate among passionate grammarians. However, it’s a requirement in APA style, so double-check all your lists and series to make sure you include it!

Capitalization After Colons and Em Dashes

If you have a colon or em dash (—) in the middle of a sentence, and what follows after is an independent clause (i.e., it could be a sentence on its own), the word after the colon or em dash should be capitalized (as though the following sentence were on its own). For example:

There was only one possible explanation: The train had never arrived.

Here, “The train had never arrived” could stand as its own sentence because it is an independent clause (i.e., it has both a subject—the train—and a verb phrase—had never arrived). Therefore, we capitalize its first word following the colon.

However, if we make one small change to this sentence, the rule changes:

There was only one possible person to blame: the train conductor.

Here, “the train conductor” cannot stand as its own sentence, so its first word following the colon is not capitalized.

Sentence Spacing

It used to be convention to type two spaces after every period—for example:

“Mary went to the store.  She bought some milk.  Then she went home.”

This convention was developed when typewriters were in use; the space on a typewriter was quite small, so two spaces were needed to emphasize the end of a sentence. However, typewriters, and therefore this practice, are now obsolete—in fact, using two spaces after sentences is now generally frowned upon. APA style in particular includes an explicit rule to use only single spaces after periods:

“Mary went to the store. She bought some milk. Then she went home.”

A Note on the Table of Contents

Because APA style is so often used for journal articles, which appear as part of a larger body of work, it does not provide guidelines for tables of contents for the individual papers themselves. If your professor asks you to include a table of contents in your paper, they will give you their own guidelines for formatting.