Writing & Grammar: Parentheses

I routinely get questions on this mechanical detail in my grammar and editing classes: does a period or comma go inside or outside of the closing parenthesis? And the answer is it depends. The way I think of it is that if the previous sentence was over before you inserted the parenthetical part, and you have a complete sentence inside the parentheses, then the period goes on the inside:

We offer classes on writing and grammar. (We also offer classes on training design, but that is a different topic.)

If the sentence was not over, and the parenthetical element is actually inside the end of your main sentence, then the period goes on the outside. That is true regardless of whether the words inside the parentheses form a complete sentence or not:

All fifteen participants took three classes last week (InDesign, Photoshop, and Captivate).

All of the participants completed the final exercise on Friday (the snowstorm had no detrimental effect on their learning).

And what about commas? Never put a comma before a parenthesis. If your main sentence needs a comma, place it after the parenthetical element:

We offered two classes last week (Proofreading for Nonproofreaders and Essentials of Adobe Captivate), but we had only 18 students registered.

Here is this week's challenge: Add parentheses, periods, and/or commas as necessary. When ready, you can send your answers directly to me.

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