How to use parentheses well is mostly about knowing when to leave them out — they’re the easiest punctuation mark to overuse, precisely because they feel so safe. Every aside, disclaimer, or afterthought can get tucked inside them. Used well, they add quiet, helpful context. Used constantly, they make writing feel like it’s interrupting itself on every line.
What Parentheses Do
Parentheses enclose extra, nonessential information — an aside, a clarification, or an afterthought — that could be removed without changing the sentence’s core meaning.
How to Use Parentheses Correctly
The test: the sentence should still make grammatical sense with the parenthetical removed entirely.
“The meeting (which ran an hour late) covered the budget.” Remove the parentheses: “The meeting covered the budget.” Still a complete, correct sentence.
Punctuation placement: if the parenthetical sits inside a larger sentence, the period goes outside the closing parenthesis. Only when the entire sentence is enclosed in parentheses does the period go inside.
Parentheses vs. Commas vs. Em Dash
All three can set off the same extra information — they just control how much attention it gets.
- Commas (blend in): “My sister, who lives in Denver, visited.”
- Parentheses (fade back): “My sister (who lives in Denver) visited.”
- Em dash (stand out): “My sister — who lives in Denver — visited.”
Same information, three different tones. Pick the one that matches how much emphasis the aside deserves.
Common Mistakes
- Overusing them. If every paragraph has a parenthetical, the writing starts to feel cluttered and hedgy.
- Putting essential information inside them. If a detail is necessary to the sentence’s meaning, it shouldn’t be parenthetical at all.
- Misplacing the closing punctuation. Remember: period outside unless the whole sentence is inside the parentheses.
- Nesting parentheses. Avoid parentheses inside parentheses — use brackets [ ] for a note inside one if it’s truly necessary.
Frequently Asked Questions
Does the period go inside or outside the closing parenthesis?
Outside, if the parenthetical is part of a larger sentence. Inside only if the entire sentence is enclosed in parentheses.
Can I start a sentence with a parenthetical?
Yes, but sparingly — it can read as clunky if overused.
Parentheses or em dash — which should I use?
Use an em dash when you want the aside to stand out. Use parentheses when you want it to fade quietly into the background.
Quick Reference
- Main use: nonessential info that could be removed without breaking the sentence
- Tone: quieter than commas or an em dash
- Period rule: outside the closing parenthesis, unless the whole sentence is enclosed
Quick practice: Punctuate correctly — “The results the full data is in the appendix were surprising.” (Answer: “The results (the full data is in the appendix) were surprising.”)