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Pesky Punctuation: Joining Dependent and Independent Clauses

Now we’ve covered the basics of punctuation by revisiting some school-day definitions and exploring terminal punctuation, it’s time to turn our attention to the second use of punctuation: joining clauses. Last week, we looked at joining independent clauses so today we’ll explore joining dependent with independent.

Once you grasp this, I promise punctuation will be so much easier. Why? Because clauses are joined by commas, colons, semicolons, and dashes—basically everything which gives everyone trouble.

Let’s put those pesky punctuation problems to bed.

3 Rules for Joining Independent & Dependent Clauses

To recap: Dependent clauses cannot stand alone and come in two types—restrictive and non-restrictive. Restrictive dependent clauses are essential to the meaning of the sentence. They limit the full meaning of the independent clause they follow. Non-restrictive dependent clauses are, as may be obvious, not essential to the meaning of the sentence. If you took it away, the independent clause would not have its meaning changed.

Dependent clauses are typically introduced by subordinating conjunctions. These are words such as: than, since, unless, because, so that, where, as though, or, and whether. They relate the clauses of a sentence by indicating comparison/degree, time, conditions/assumption, reason/concession, purpose/result, place, manner, appositions (and, or), and indirect questions.

But the trick to joining independent and dependent clauses is really in knowing the difference between restrictive and non-restrictive clauses. Once you’ve got that down, apply the following rules for punctuation.

Rule #1  When a dependent clause comes before an independent clause, use a comma. (DEP, IND)

“Even though your computer may automatically back up files, it is a good idea to keep them on an external hard drive.”

“If the dog doesn’t wear its holiday bow tie, the picture will be ruined.”

“When we go to the store, don’t forget to buy some apples.”

Rule #2  When a restrictive dependent clause comes after an independent clause, no comma is needed. (IND R-DEP)

“The picture will be ruined if the dog doesn’t wear its holiday bow tie.”

“I can’t bake pie unless we go to the store for apples.”

Rule #3  When a non-restrictive dependent clause comes after an independent clause, a comma is needed. (IND, NR-DEP)

“Documents should be backed up on an external hard drive, even though the computer will automatically do so in its internal memory.”


At times, dependent clauses will be introduced by a relative adjective (whose), a relative adverb (where, where), or a relative pronoun (that, who, which). Together, these are called relative clauses and are also restrictive or non-restrictive, so they also follow the rules above.

Restrictive: “Dogs that are blind require special attention and care.” The use of “that” restricts which dogs “require special attnetion and care”, so no comma is needed (IND R-DEP).

Non-restrictive: “Dogs, which make great pets, are great for teaching responsibility.” The non-restrictive dependent clause is enclosed be commas (IND. NR-DEP), as if we took it away it would not alter the meaning of “Dogs are great for teaching responsibility.”

Relative clauses can also function as appositives, which rename the subject or add a new piece of information: “My father, the inventor of toaster strudel, will not be happy about this.” These, by nature, are non-restrictive and may also be used with and or or. It is common for these phrases, surrounded by commas, to be called parenthetical. In other words, they are not really necessary to understand the meaning of the sentence.

In short, commas are used to set off non-restrictive clauses, but not with restrictive.

Things to Watch For…

Pitfall #1: Restrictive or Non?

Once and awhile, determining if a dependent clause is restrictive or not is quite tricky. For example, “She was mad when her mother-in-law dropped by”, means that this unexpected event is what caused the woman’s anger. As there is no comma to separate the elements and indicate they are unrelated, the clause is restrictive.

However, if we were to use a comma—“She was mad, when her mother-in-law dropped by”—this means that the woman was already mad when her mother-in-law showed up. The presence of the comma separates the two elements and suggests there is no relation between them, making it non-restrictive.

Pitfall #2: Because Clauses

Whether a clause is restrictive or non-restrictive also dictates if a comma is used with a because clause. When we use “because” we are illustrating a relationship of sorts, and whether this is a negative or positive relationship determines when or if to use punctuation.

Negative: If the because clause is preceded by a negative independent clause, the same principal in Pitfall #1 applies: “The dog didn’t win, because of its rare breed.” The comma makes this non-restrictive, separating the two elements. Really, this is taken to mean that the dog didn’t win, and the reason they didn’t win was because they are a rare breed.

However, if the comma is removed—“The dog didn’t win because of its rare breed”—this makes the dependent clause restrictive and signals the clear relationship between the two. Careful readers will realize that the missing comma really means this sentence reads “The dog did win, but its rare breed was not the reason.” To avoid confusion, this sentence should be reworded.

Positive: But what if the preceding independent clause is affirmative? The presence, or not, of a comma will shift the emphasis. Using one represents assertion, while the absence emphasizes the reason. Consider the following sentence:

“The racers must be registered, because official times will only be posted by bib number.”

“The racers must be registered because official times will only be posted by bib number.”

Without the comma the dependent clause becomes non-restrictive; the emphasis is on the reason why the racers must register. Restrictive, with the comma, it is stressed simply that racers must register, the reason only added on.

That was a lot of information, but really taking the time to make sure you grasp these concepts and rules will help you that much more. It will make you a better writer, and better able to impart meaning to your readers.

Leave any questions or comments below. Next week we wrap things up with the final use of punctuation: setting off phrases.

Happy Writing!



1. The Copyeditor’s Handbook, 3rd Ed.

2. The Chicago Manual of Style, 17th Ed

Jennifer DinsmoreComment