Does “Because” Need a Comma?

Perhaps you’ve already read our article on how to use commas. You know the basic comma rules. You feel your comma confidence increasing. Ah, you think to yourself, look at the fine way this author uses commas! Then, just when you think you understand the punctuation mark fully, you notice something that can only be described as a grammar loophole. All the rules seem to suggest that a comma isn’t necessary; yet, without it, the sentence lacks common sense. Without the comma, you’re left with ambiguity—a writer’s worst nightmare. 

We didn’t win the race because it rained.

It’s unclear whether the sentence above means, “We lost the race because it rained,” or “The rain isn’t what made us win the race.” The lack of clarity could lead to a misreading of the author’s intent. 

Typically, the word “because” acts as a dependent marker word, also known as a subordinating conjunction. This means that, when you have two independent clauses, placing “because” between them makes the second clause into a subordinate clause. So, if you take two independent clauses, and connect them with a subordinating conjunction, you normally don’t need a comma. 

We didn’t win the race. It rained.

We didn’t win the race because it rained.  

In the example above, you shouldn’t need a comma, according to the laws of English grammar. “It rained” has become subordinate. And yet…the meaning of the sentence isn’t clear.

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The Common Sense Test

Generally, there are two situations in which the word “because” introduces confusion into a sentence in the English language. First, a sentence with a negative independent clause followed by “because” will often cause problems. Next, a sentence can become unclear when there are two possible elements to which the “because” could refer. In either of these circumstances, it’s important to adjust your sentence so that it passes the common sense test. For example, we can suggest a few ways to improve the clarity of the sentence, “We didn’t win the race because it rained.” 

  1. We didn’t win the race, because it rained. (We lost.)
  2. We didn’t win the race because it rained, but because we ran faster than the other team. (We won.)
  3. Because it rained, we didn’t win the race. (We lost.) 

You can see that we’ve introduced commas in all three sentences. In the first sentence and the third sentence, the meaning is clear: the rain caused us to lose the race. In the second sentence, the rain did not cause us to win; instead, another factor influenced our victory. By adding a comma, a coordinating conjunction, and another clause, we clarify the meaning. 

If you don’t think that commas are important, think again! In the examples above, the punctuation signals the difference between victory and defeat.

Choosing Between Two Elements

With the previous example, you can see how a negative clause (didn’t, couldn’t, wouldn’t) led to confusion when it preceded “because”. Now, let’s look at an example where the meaning of the sentence hinges on two grammatical elements. 

She thought she missed the meeting because he told her it was at 3 p.m.

There are two possible interpretations for this sentence. 

  1. Because he told her it was at 3 p.m., she thought she had missed the meeting. (Still can attend the meeting.)
  2. She thought, “I missed the meeting because he told me it was at 3 p.m.” (Missed the meeting.)

Again, the ambiguous construction leaves the reader to decide between two very different meanings. The word “because” has a two-part reference. It’s unclear whether “because” provides a reason for why “she thought” or why “she missed.” To avoid this confusion, it would be best to restructure the sentence. 

No Need for Commas with Subordinating Conjunctions

Outside of the two scenarios given above—a negative independent clause and structural ambiguity—you’ll never need a comma before the word “because” in a simple sentence. 

Let’s look at a few straightforward sentence constructions:

I ate the pasta because I liked it. 
She graduated because she finished her courses. 
The dog barked because he heard a loud noise.

There’s no need for a comma in these examples. Of course, in any of these sentences, you could add a parenthetical idea that does require commas. 

I ate the pasta, a whole wheat tortellini, because I liked it. 

By adding an appositive, a word or phrase that renames the noun before it, you give the reader more information about the pasta. Any appositive needs to be set apart from the rest of the sentence. In this case, a set of commas does the job nicely. Of course, any nonrestrictive, or inessential, clause requires the same handling. If a phrase or clause does not give information necessary to the meaning of the sentence, it should be sectioned off with commas. 

Here’s another example:

The dog barked, exercising his soulful voice, because he heard a loud noise.

When you introduce a nonrestrictive phrase, you’ll sometimes need to place a comma before the word “because.” This has nothing to do with the word “because” and everything to do with the general rules for comma usage

Introductory Phrases

Most of the time, you’ll use “because” to show causation by placing it between the main clause and secondary clause at the end of a sentence. The secondary clause becomes subordinate to the main clause with the addition of the subordinating conjunction. 

Other times, you’ll use the word “because” at the beginning of a sentence to begin an introductory clause. You can use other subordinating conjunctions this way as well—after, although, as, if, since, when, and while. When you use this sentence structure, be sure to include a comma after the introductory clause. This allows the reader to take a slight pause, separating the introductory phrase from the rest of the sentence. 

Because she finished her courses, she graduated. 

Practice

Do the following sentences need commas? Answer yes or no. 

  1. Because he was tired he slept. 
  2. Jessica moved to New York because she wanted to be an actress. 
  3. Her writing tips didn’t make sense because she forgot important grammar rules. 
  4. He used quotation marks because he wrote dialogue. 
  5. He started his job at Google and began coding because he wanted to become an engineer. 
  6. She basted the turkey the centerpiece of her Thanksgiving meal because she wanted a juicier bird.

1) Y 2) N 3) Y 4) N 5) Y 6) Y

It’s possible to revise some of these sentences to make them easier to read:

  1. Because he was tired, he slept. 
  2. Jessica moved to New York because she wanted to be an actress. (No change.)
  3. Her writing tips didn’t make sense, because she forgot important grammar rules. 
  4. He used quotation marks because he wrote dialogue. (No change.)
  5. He began coding because he wanted to become an engineer.
  6. She basted the turkey, the centerpiece of her Thanksgiving meal, because she wanted a juicier bird.

Sources:

  1. https://style.mla.org/comma-sense/
  2. https://www.chicagomanualofstyle.org/qanda/data/faq/topics/Commas/faq0018.html
  3. https://owl.purdue.edu/owl/general_writing/punctuation/commas/extended_rules_for_commas.html