Punctuation

Punctuation gives a sentence a rhythm or flow, and good punctuation is an important part of writing. Some punctuation marks tell us where to stop, like periods and question marks. Other punctuation marks tell us where to pause, like commas, semicolons and colons. And some punctuations marks tell us where a sentence detours, like dashes, parentheses and square brackets. This section is adapted from Chapter 6 of the Publication Manual of the American Psychological Association (the Publication Manual), and from the Learning Portal. You can find a link to the Learning Portal at the end of this chapter. This section outlines the most common punctuation marks and explains how to use them to communicate well in writing. This section is only a summary; students and instructors should consult the Publication Manual for more details.

Spacing After Punctuation Marks (6.1)

Insert one (1) space after the following:

• Periods or other punctuation at the end of a sentence
• Commas, colons, and semicolons
• Periods that separate elements in a reference list entry
• Periods after initials in names, e.g.: S. W. Chantler

Do not add a space after the following:

• After periods used in an abbreviation, e.g: U.S.A
• Around colons in ratios, e.g.: 2:4
• After periods in initials or other labels that are used to protect the identity of participants in a study, e.g.: E.R.F.

Types of Punctuation Marks

Periods (6.2)

Use a period in the following cases:

• At the end of a complete sentence
• With initials in names, e.g.: W. P. Kinsella
• In the abbreviations for “United States” and “United Kingdome” when the abbreviation is used as an adjective, e.g.: U.S. Navy
• Ln labels used to protect the identity of participants in a study, e.g.: C.S.D.
• In Latin abbreviations, e.g.: a.m, p.m., i.e., etc.
• In abbreviations in reference list entries, e.g.: Vol. 1, 3rd ed., p. 14, etc.
• In designations for eras of time, e.g.: B.C.E., A.D., etc.
• After each element in a reference list entry, except DOIs and URLs

Do not use periods in the following cases:

• In abbreviations of provinces, territories or states, e.g.: ON, BC, NY, etc.
• In capital letter abbreviations and acronyms, e.g.: APA
• In abbreviations for academic certifications, e.g.: BScN, PhD, etc.
• In abbreviations of units of measurement, e.g.: cm, kg, ml, etc.
• In abbreviations for routes of administration, e.g.: iv (instead of “intravenous”)
• After URLs in the body of an essay or assignment
• After DOIs or URLs in a reference list entry

Commas (6.3)

Use a comma in the following cases:

• Between independent clauses if they are connected by a coordinating conjunction, e.g.: I wanted to go, but I couldn’t afford to buy a ticket.
• To separate listed items if there are three or more items in the list, e.g.: red, white, and blue
• To separate listed adjectives, e.g.: She drives an old, beat-up car.
• Before and after non-essential material,  e.g.: John Smith, who went to Loyalist College, is the president of the company.
• After transitional words or phrases such as therefore, however, thus, first, second, etc., e.g.: First, I took out my keys, and then, I unlocked the door.
• Around additional information that interrupts a sentence, e.g.: Bagels, for example, are delicious with cream cheese.
• For direct quotations. When a direct quotation is used, a comma is placed after the word that declares the direct quotation, e.g. Her sister asked, “Are you done with your homework?” When a direct quotation is before the declaring word, a comma is placed at the end of the quotation within the quotation marks, e.g. “I’m working on my assignment,” replied Sarah.
• To separate a dependent clause from an independent clause, e.g.: From the beginning, the plot of the film was obvious.
• To separate items in an address or a date, e.g.: Friday, July 14, 1978

Semicolon (6.4)

Use a semicolon in the following cases:

• To separate independent clauses that have closely related ideas, e.g.: The instructor had a good sense of humour; nevertheless, she was strict.
• To separate items in a list that already contain commas, e.g.: The colour groups were red, yellow and blue; orange, green, and purple; and black, grey and white.
• To separate multiple parenthetical citations, e.g.: (Velentzas, 2022; Gauld et al., 2019)

Colon (6.5)

Use a colon in the following cases:

• To introduce a list, e.g.: There are three parts of a reference list entry: the author, the date, the title, and the source.
• In ratios, e.g.: The proportion of water to bleach was 10:1.

Dash (6.6)

There are two kinds of dashes used in APA Style:

• Em Dash
  • The em dash is the long dash: —
  • Em dashes are used to offset an element which has been added to amplify or digress from the main clause in a sentence.
  • Use em dashes sparingly; overusing them can weaken the flow of written work.
  • Do no add a space before or after an em dash
  • e.g.: The Library’s current hours of operation—8:00 am to 7:00 pm—change in the summer.

• En Dash
  • The en dash is the shorter dash: –
  • En dashes are used between words of equal weight in a compound adjective, or to indicate a numerical range.
  • Do not add a space before or after an en dash
  • e.g.: pp.105-127, Toronto-London flight, 60%-75%

Parentheses (6.8)

Parentheses, which are sometimes called “brackets”, are used in several ways:

• For in-text citations, e.g.: (Dawson, 2023), or Dawson (2023) described . . .
• To set off independent elements, e.g.: The pattern was statistically significant (see Figure 2).
• To introduce an abbreviation, e.g.: The Canadian Broadcasting Corporation (CBC), Acquired immune deficiency syndrome (AIDS)
• To set off letters that identify items in a list that appears within a sentence or paragraph, e.g.: The study included (a) students at
• To group mathematical expressions, e.g.: The word “novel” could mean (a) new or not previously identified, or (b) a work of prose fiction.

Do not use parentheses in the follow cases:

• To enclose text within other parentheses. Instead, use square bracket, e.g.: (Ankylosing Spondylitis [AS]; Matteson & Woywodt, 2006)
• To enclose statistics that already have parentheses. Instead, use a comma before the statistics, e.g.: . . . were significantly different, F(4, 132) = 13.62
• To enclose back to back parenthetical information. Instead, put the information into one set of parentheses, separated with a semicolon, e.g.: (e.g.: taxonomy; Pavlinov, 2022)

Square Brackets (6.9)

Square brackets are used in the following cases:

• To enclose parenthetical information that is already in parentheses, e.g.: She did everything on her own. (She never asked his friends [or anyone else] for help.)
• To enclose abbreviations when the abbreviated term is already in parentheses, e.g.: (The APA [American Psychological Association] stated . . . )
• To enclose information inserted into a quotation by someone other than the original author, e.g.: Velentzas’s review (2023) noted that, “The clean and appealing design of the book is beautifully matched to [Tom] Gauld’s cartoon aesthetic.”

Do not use square brackets in the following cases:

• To set off statistics that are already in parentheses, e.g.:
  • Correct: . . . in the first study, F(1, 32) = . . .
  • Incorrect: . . . in the first study (F[1,32] = . . .)
• Around the date of publication in a narrative citation if the sentence that contains the narrative citation is already in parentheses, e.g.:
  • Correct: (as Stephens, 2022, noted . . .)
  • Incorrect: (as Stephens [2022] noted . . .)

Capitalization (6.13-6.21)

APA Style uses two types of capitalization:

• Title case: most words are capitalized in the title or heading, e.g.: The Loyalist College Guide to APA Style and Academic Writing
• Sentence case: most words are lowercase in the title or heading, e.g.: Nurse educators’ critical thinking: A mixed methods exploration
  

How and when should I use title case? (6.17)

• Capitalize the first word in a title or heading, and the first word in a subtitle
• Capitalize the first word after a colon, em dash, or end punctuation in a heading
• Capitalize major words, including the second part of hyphenated words, e.g.: “Self-Report”, not “Self-report”
• Lowercase is only used for short conjunctions (and, as, but, for, if, nor, or, so, yet), articles (a, an, the), and short prepositions (as, at, by, for, in, of, off, on, per, to up, via)
• Use title case for:
  • Titles of article, books, reports, and other works appearing in text, e.g.: The textbook, titled, The Role of the Nurse Educator in Canada, is available in the bookstore.
  • Titles of tests or measures, e.g.: The Beck Depression Inventory was created by Aaron T. Beck . . .
  • All headings
  • The title of your own essay or assignment, including named sections and subsections, e.g.: My essay was titled, Pain Management for Hip Replacements: A PICOT Analysis.
  • Titles of periodicals, e.g.: I used the Canadian Journal of Nursing Research for my essay.
  • Table titles; these should also be italicized, e.g.: Table 1 is titled, Pain Management Outcomes.
  • Figure titles; these should also be italicized, e.g.: Figure 2 is titled, Anatomy of a Hip Replacement.

How and when should I use sentence case? (6.17)

In sentence case, most words in the title or heading are lowercase. Capitalize only the following words:

• Capitalize only the first word in a title or heading
• Capitalize the first word of a subtitle
• Capitalize the first word after a colon, em dash, or end punctuation in a heading
• Capitalize nouns followed by numerals or letters
• Capitalize proper nouns
• Use sentence case for the titles of articles, books, reports, webpages, and other works in reference list entries, even if title case was used for the original work, e.g.: The role of the nurse educator in Canada
• Use sentence case for table column headings, entries, and notes
• Use sentence case for figure notes

In APA Style, words are capitalized in the following situations:

• The first words of a complete sentence.
• The first word after a colon if what follows is a complete sentence
• Proper nouns and adjectives.
• Names of racial and ethnic groups.
• Names of specific university or college departments, academic institutions, and academic courses
• Trade and brand names, e.g.:; do not include the copyright or trademark symbol with these names in an academic essay, e.g.:  However, these symbols are included in marketing materials.
• Tiles or job names when the title comes before a name, e.g.: Prime Minister Jean Chrétien was elected in 1993.
• Names of diseases or disorders, therapies, treatments, theories, concepts, hypotheses, models, or statistical procedures, if the name contains a proper name, such as the individual who discovered or names the condition, e.g.: Alzheimer’s disease, Maslow’s hierarchy of needs.

Do not capitalize the following:

• A personal name that begins with a lowercase letter when then name begins a sentence, e.g.: Gloria Jean Watkins  wrote under the pen name bell hooks.
  • bell hooks used only the lowercase spelling of her name.
• A proper noun other than a personal name that begins with a lowercase letter, e.g.: iPad, eBay, when it is used at the beginning of a sentence, or a lowercase statistical term, e.g.: t test, when it is used at the beginning of a sentence. Instead, reword the sentence to avoid beginning with a lowercase letter.
• Proper adjectives that have a common meaning, except for personal names within these terms. Check a dictionary for guidance.
• Titles or job names when the title comes after a name, e.g.: Jean Chrétien was elected prime minister in 1993.
• Names of diseases or disorders, therapies, treatments, theories, concepts, hypotheses, models, or statistical procedures, e.g.: diabetes, leukemia, etc., unless the name contains a proper name. (See the example above.)

Italics (6.22)

Italics are used in the following cases:

• Key terms or phrases, including those accompanied by a definition, e.g.: Psychology is defined as . . .
  • Italics for a term or phrase are only used once, when it makes the most sense to draw a reader’s attention to that word or phrase. It should appear in regular, non-italic font everywhere else in the essay or assignment. For example, if an important word or phrase appears for the first time in a heading and it is then defined in the text under the heading, italicize the word or phrase the first time it appears in the text, not in the heading.
• Titles of books, reports, webpages, and other standalone works, e.g.: We used The Publication Manual of the American Psychological Association for to help us with our citations.
• Titles of periodicals, including journals, e.g.: Psychology Today was first published in 1967.
  • Remember that this is also true in reference list entries.
• Periodical volume numbers when they appear in reference lists, e.g.: Psychology Today, 7 (2)
• Genera, species and varieties, e.g.: Felis catus is the Latin name for the common domesticated cat.
• Anchors of a scale, but not the associated number, e.g.: Results ranged from 1 (poor) to 5 (excellent).

Do not italicize the following:

• Titles of book series, e.g.: the Hunger Games series
• Any punctuation marks that appear after an italicized word or phrase, e.g.: What is psychology?
• Punctuation between elements in a reference list entry, e.g.: the comma after a volume and issue number, or the period after a book title
• Words, phrases or abbreviations in another language that appear in a dictionary for the language in which you are writing, e.g.: et al. (Latin), cliché (French)
• Letter used as abbreviations
• Do not italicize simply for emphasis, unless the emphasis might be lost or misread.
• Chemical terms, e.g.: LSD, MDMA
• Trigonometric terms, e.g.: sin, tan, log

Sources

American Psychological Association. (2020). Publication manual of the American Psychological Association: The official guide to APA style. (7th ed.).

College Libraries Ontario. (2024). Grammar and punctuation. The Learning Portal. https://tlp-lpa.ca/writing/grammar