Summary
Parentheses (round brackets) are common in academic and scientific writing, but the punctuation and formatting around them are often inconsistent or incorrect. In formal prose, the punctuation belongs primarily to the sentence, not to the bracketed material, and errors such as placing commas or full stops inside parentheses when they logically belong outside can make a sentence look clumsy or even misleading. Nested brackets, back-to-back parentheses, and the interaction between parentheses and dashes add further complexity.
This article explains how to punctuate and format correctly when using parentheses in running text. It covers the relationship between parentheses and dashes, when commas, semicolons, full stops, question marks, and exclamation marks should appear inside or outside brackets, how to handle numbered lists, and the difference between British and American conventions for nested brackets. It also offers guidance on avoiding awkward constructions such as embedded full sentences inside another sentence’s parentheses, and on rewording to minimise double or back-to-back brackets.
By following these straightforward rules and applying a few practical checks as you proofread, you can ensure that your use of parentheses supports clarity and precision instead of distracting your readers or confusing your argument.
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Punctuating and Formatting Correctly in Relation to Parentheses
1. Why Parentheses Need Careful Handling
Parentheses – also called round brackets – are used very frequently in academic and scientific writing. They help you add clarifications, examples, references, abbreviations, and brief comments without interrupting the main flow of the sentence. However, because parentheses create a “sentence inside a sentence,” they often confuse punctuation and formatting. A comma that looks harmless in ordinary prose can suddenly feel awkward when it appears next to a closing bracket. A full stop placed in the wrong position can subtly change what appears to be part of the main sentence and what appears to be merely an aside.
Fortunately, the rules for punctuation around and within parentheses in running text are straightforward once you understand where the punctuation logically “belongs”: to the main sentence, to the parenthetical material, or to both. This article focuses on that general use of parentheses in normal scholarly prose, not on specialised uses in mathematics, linguistics, or legal documents, which follow their own conventions.
2. Parentheses and Dashes: How They Interact
Parentheses and dashes are both devices for marking off additional information, but they behave slightly differently. Parentheses tend to downplay the importance of the enclosed material; dashes give it stronger emphasis. Sometimes you may need to use both in the same sentence.
2.1 Parentheses inside a dash-marked clause
Parentheses can be used within a parenthetical clause that is already marked off by dashes. For example:
Three kinds of birds returned in the spring – robins, chickadees (the smallest) and sparrows – and then left again in the fall.
Here, the em dashes set off the list as an aside, and the parentheses add extra information about one item in that list. This structure is perfectly acceptable in academic writing as long as the sentence remains readable.
2.2 Dashes inside parentheses
Conversely, you can place dashes inside a parenthetical clause:
Three kinds of birds returned in the spring (robins, chickadees – the smallest – and sparrows) and left again in the fall.
In this sentence, the entire list is inside parentheses, and the dashes highlight a short explanatory comment about chickadees. Note that the parentheses still belong to the main sentence, and the punctuation inside them follows normal rules.
In both patterns, the goal is to keep the sentence comprehensible. If using both dashes and parentheses makes the structure too complex, rephrasing the sentence is often better than adding more punctuation.
3. Commas, Semicolons, and Parentheses
One of the most common questions about parentheses concerns the placement of commas and semicolons. The basic rule is simple: a comma or semicolon belongs inside the parentheses only if it logically belongs to the parenthetical material; otherwise, it belongs outside, where it would appear if the parentheses were removed.
3.1 Commas before opening parentheses
A comma or semicolon should precede an opening parenthesis only in a numbered list where the numbers themselves are enclosed in parentheses:
Four conditions were created for the experiment: (1) darkness inside, (2) darkness outside, (3) artificial lighting inside and (4) daylight outside.
Here, the commas separate the list items, and the parentheses enclose the list numbers. The commas would still be correct if the numbers were not in parentheses, so they may precede the opening bracket.
In ordinary prose, however, you do not usually place a comma or semicolon just before an opening parenthesis. Instead, you punctuate the sentence as if the parentheses were not there, then insert the brackets around the parenthetical element.
3.2 Commas after closing parentheses
A comma or semicolon should never precede a closing parenthesis. If a sentence requires a comma immediately after a parenthetical phrase, the comma follows the closing bracket:
After crawling through the window (on the third floor), she unlocked the door.
Here, the comma belongs to the main sentence, which would read “After crawling through the window, she unlocked the door” with the parenthetical phrase removed. Writing “(on the third floor,)” incorrectly attaches the comma to the parenthetical material instead of to the sentence.
4. Full Stops, Question Marks, Exclamation Marks
Full stops (periods), question marks, and exclamation marks follow a similar principle: place them outside the parentheses if they relate to the sentence as a whole, and inside if they relate only to the parenthetical material.
4.1 Punctuation outside the parentheses
When the main sentence requires punctuation at the end, that mark comes after the closing parenthesis:
I worked for days to polish my thesis, yet my external examiner had the audacity to say something truly insulting (“It doesn’t look like you proofread this at all”)!
In this example, the exclamation mark expresses the writer’s reaction to the entire sentence. The quoted remark inside parentheses does not itself require an exclamation mark, so the punctuation appears after the closing bracket.
4.2 Punctuation inside the parentheses
When the parenthetical material alone is interrogative or exclamatory, the mark appears inside the parentheses:
It may be November, but it was as warm as summer yesterday (can you believe it?).
Here, the question mark belongs to the mini-question inside the brackets; the sentence as a whole is a statement, so no extra question mark is required outside.
4.3 Full sentences inside parentheses
Sometimes the parenthetical element is a complete sentence on its own. In that case, the full stop should appear inside the parentheses, and the parenthetical sentence should not be embedded inside another sentence:
This pattern appears throughout the dataset. (A detailed breakdown is provided in Appendix A.)
Notice that the second sentence is fully parenthetical and stands separately. By contrast, constructions such as “This pattern appears throughout the dataset (A detailed breakdown is provided in Appendix A.) and supports our hypothesis” are awkward because they embed a complete sentence within another sentence.
5. Nested Parentheses: British vs American Practice
Occasionally you may need to use brackets within brackets – for example, if you want to give a percentage in parentheses after a number that is already inside parentheses. Practices differ slightly between varieties of English.
5.1 British English: parentheses within parentheses
In British English, it is acceptable to use round brackets within round brackets in running prose if needed:
(34 men (50%) and 34 women (50%))
While this is grammatically acceptable, repeated nesting can be hard to read. It is generally best to keep such double bracketing to a minimum and to consider rephrasing the sentence instead.
5.2 American English: square brackets inside parentheses
In American English, the usual practice is to place square brackets inside parentheses:
(34 men [50%] and 34 women [50%])
If further nesting is required, parentheses then appear inside those square brackets, and so on. Again, in ordinary scholarly prose, heavy nesting is discouraged; it is usually better to recast the sentence or to move some information to a footnote.
5.3 Avoiding back-to-back and excessive brackets
Regardless of variety of English, it is good practice to avoid:
- long chains of nested brackets, and
- back-to-back parentheses such as “(see Table 1) (for details)” in the main text.
When you find yourself writing several sets of brackets in a row, it is almost always possible – and preferable – to rewrite the sentence so that the information is integrated more smoothly or moved to a separate sentence.
6. Parentheses in Numbered Lists
Parentheses are frequently used to enclose item numbers in inline lists, especially in academic styles. The example quoted earlier illustrates the standard pattern:
Four conditions were created for the experiment: (1) darkness inside, (2) darkness outside, (3) artificial lighting inside and (4) daylight outside.
Here, the punctuation rules from above still apply:
- Commas separate list items and may appear before opening parentheses that surround the numbers.
- There is no comma or semicolon before a closing parenthesis.
- Spacing before and after each parenthetical number should be consistent.
In running text, avoid mixing different styles of numbering (for example, switching between parenthesised numerals, roman numerals, and bullets without a clear reason). Parenthesised numerals are particularly useful when you want to refer back to specific conditions or items later in the text (“Condition (2) showed the highest variance”).
7. Practical Tips for Using Parentheses in Academic Writing
To make your use of parentheses both correct and reader-friendly, consider the following practical guidelines as you draft and revise:
7.1 Ask whether the information really needs parentheses
Because parentheses visually downplay the enclosed material, ask whether the information is genuinely peripheral. If the content is important for understanding the argument, it may deserve to be part of the main sentence or even a separate sentence. Overuse of parentheses can make prose feel fragmented and hesitant.
7.2 Test the sentence without the parenthetical element
A simple test for punctuation placement is to remove the parenthetical material and see what remains:
- If the sentence is grammatically correct without the bracketed material, the basic punctuation should attach to that outer sentence.
- If the sentence collapses or feels incomplete when you remove the brackets, the structure may need rethinking.
This test also clarifies where commas and full stops belong – usually outside the parentheses if they are required by the main sentence.
7.3 Be consistent with your variety of English
Decide early whether you are following British or American conventions and then keep that choice consistent throughout your document. This affects not only punctuation and spelling, but also the use of nested brackets (round inside round vs round with square inside).
7.4 Avoid embedding full sentences inside others
When you need to include a full sentence in parentheses, place it between two complete sentences rather than embedding it mid-sentence. For example:
The sample size was limited to 60 participants. (A full justification of the sample size is provided in Section 3.4.) The results should therefore be interpreted with caution.
This arrangement keeps each sentence intact and easier to read.
7.5 Check for punctuation crowding
When you use multiple types of punctuation near parentheses – such as quotes plus brackets plus exclamation marks – read the sentence aloud and check that the visual layout is not too crowded. If necessary, split the sentence into two or simplify the structure.
8. A Quick Checklist for Parentheses
As a final step in editing, you may find this checklist helpful:
- Have I used parentheses only where the information is truly parenthetical?
- Do commas, semicolons, and full stops appear outside the closing parenthesis when they belong to the main sentence?
- Do punctuation marks appear inside the parentheses only when they belong solely to the parenthetical material (for example, in a mini-question or a complete parenthetical sentence)?
- Have I avoided nesting brackets unnecessarily and reworded sentences that contained back-to-back parentheses?
- In inline numbered lists, have I punctuated consistently and placed commas correctly?
- Have I chosen British or American conventions for nested brackets and applied them consistently?
Parentheses are powerful tools for adding nuance and precision to scholarly writing. Used thoughtfully and punctuated correctly, they can help you present complex information clearly without disrupting the flow of your argument.
