Punctuation with Parentheses and Brackets
Summary
The general rule is that punctuation goes within parentheses or brackets if it belongs to the parenthetical text, but outside if it belongs to the surrounding sentence. Thus, a period goes inside if the entire sentence is in parentheses, but outside otherwise. Similarly, question marks, exclamation points, and quotation marks appear within parentheses if they are meant to punctuate the text inside parentheses. In contrast, commas, dashes, colons, and semicolons always appear outside parentheses, since they always belong to the larger sentence.
Periods with parentheses and brackets
Place a period inside parentheses if the sentence ends within the parentheses.
- The deadline is 4 p.m. (Applications will not be accepted after that time.)
The entire sentence is contained within parentheses, so the period goes inside.
- My cat loves cheese. (She also likes pizza.)
- Anita is studying xenarthrans in Latin America. (Xenarthrans are an unusual group of mammals comprising sloths, anteaters, and armadillos.)
However, if the text in parentheses is part of a larger sentence, place the period outside to end that sentence.
- The deadline is 4 p.m. (after which time, no application will be accepted).
The parenthetical text appears within a larger sentence, which ends after the closing parenthesis.
- Cats love cheese (almost as much as pizza).
- Anita has moved to Latin America to study xenarthrans (sloths, anteaters, and armadillos).
If a sentence is entirely contained within parentheses and has its own period, remember to also punctuate the sentence before it.
- Incorrect: She was earlier in Australia studying monotremes (Monotremes are egg-laying mammals.)
Correct: She was earlier in Australia studying monotremes. (Monotremes are egg-laying mammals.)
Square brackets are used within parentheses as brackets within brackets. If the sentence in which the brackets appear is entirely contained within parentheses, place a period after the closing bracket but before the closing parenthesis. If the parenthetical text is part of a larger sentence, place the period outside.
- The humble snake plant is almost unkillable. (See The Green Guide to Houseplants [1997].)
- Tectonic activity decreased in the region. (Tremors were concentrated to specific locations [see Klintberg 2011].)
- The humble snake plant is almost unkillable (The Green Guide to Houseplants [1997]).
- Tectonic activity decreased in the region (but was concentrated to specific locations [see Klintberg 2011]).
In British usage, round brackets are used within round brackets. Place the period (or full stop) depending on what you are punctuating: the text within or outside brackets.
- Cacti are the easiest plants to grow indoors. (See The Green Guide to Houseplants (1997).)
- Cacti are the easiest plants to grow indoors (see The Green Guide to Houseplants (1997)).
Question marks and exclamation points with parentheses
Place a question mark or exclamation point before a closing parenthesis to punctuate the text inside parentheses. If the punctuation mark is meant to punctuate the surrounding sentence, place it after the closing parenthesis.
- We should order food. (How about pizza?)
- We should order food (pizza?).
- Let’s order food (not pizza!).
- Let’s get some food. (Just don’t order pizza!)
- Can we meet soon (today, if possible)?
Quotation marks with parentheses
Quotation marks go inside parentheses if the quoted text is contained entirely within parentheses. If the parenthetical text is part of a larger quote, the quotation marks go outside.
- Our apartment had a tiny window balcony (which the listing called a “patio”).
- Leave feedback but kindly. (“This sentence is unclear; please consider rephrasing.”)
Commas, dashes, colons, semicolons with parentheses
When commas, dashes, colons, and semicolons appear at the end of parenthetical text, they always go outside parentheses, since they always belong to the surrounding sentence.
- Incorrect: Some marine mammals (like the Caribbean monk seal,) which were targeted by commercial fishing, have gone extinct.
Correct: Some marine mammals (like the Caribbean monk seal), which were targeted by commercial fishing, have gone extinct. - Incorrect: Many marine species—mammals in particular (like the Caribbean monk seal—) have gone extinct.
Correct: Many marine species—mammals in particular (like the Caribbean monk seal)—have gone extinct. - Incorrect: Commercial fishing has affected marine populations (mammals in particular:) some have even gone extinct.
Correct: Commercial fishing has affected marine populations (mammals in particular): some have even gone extinct. - Incorrect: Commercial fishing has affected marine populations (mammals in particular;) some have even gone extinct.
Correct: Commercial fishing has affected marine populations (mammals in particular); some have even gone extinct.