Comma Before Because | Rules & Examples
You normally shouldn’t use a comma before ‘because’ when the reason that ‘because’ introduces is essential to your meaning. For example, the point of the sentence below is to give a reason for good grammar’s importance.
When you add a comma before ‘because’, it removes the emphasis from the reason it introduces. The main point of the sentence below is simply to state the importance of good grammar; the reason is an afterthought.
When to use a comma before ‘because’ in positive statements
In a positive statement (one that doesn’t include ‘not’), adding the comma before ‘because’ draws the reader’s focus to what comes before it as the main point of the statement. Leaving it out makes them focus on the ‘because’ clause.
The choice is often informed by the surrounding context. Consider the example below.
The point of these sentences is to contrast the two subjects’ reasons for going to bed late. It wouldn’t make sense to add a comma to either sentence; the ‘because’ clauses are the main point (they’re called restrictive clauses or essential clauses).
Now consider another example where the comma is added.
The point of this sentence is that, despite staying up late, Colin still woke up on time. His reason for staying up late is included but not essential. It’s a nonrestrictive or nonessential clause. It could just as well be placed in parentheses, set off by em dashes, or removed.
When to use a comma before ‘because’ in negative statements
The issue is slightly different in a negative statement (one that includes the adverb ‘not’ or a contraction like ‘didn’t’ or ‘won’t’). This is because there’s some ambiguity about whether the ‘because’ clause represents:
- An incorrect reason for something that did happen, or
- A correct reason something didn’t happen
When the ‘because’ clause indicates an incorrect reason, you should leave out the comma. Consider the example below.
From these sentences, it’s clear that people do in fact listen to the person being discussed but that it’s not because of his controversial statements.
Note that the first sentence alone would be ambiguous. The context is needed to clarify whether it’s the ‘because’ clause or the ‘people listen’ clause that’s being negated. With sentences like this, it’s important to either provide the necessary context (as above) or rephrase:
- People don’t listen to him because he makes controversial statements.
- It’s not because of his controversial statements that people listen to him.
When the ‘because’ clause correctly describes why something didn’t happen, you should add a comma before ‘because’. This lets the reader know that the ‘because’ clause gives the reason for the negative statement. Consider the example below.
From this sentence, it’s clear that people actually don’t listen to the person in question and that the reason for this is his controversial statements.
Unlike with the previous examples, the inclusion of the comma makes this clear from this sentence alone. There’s no possibility of misreading and no need to rephrase or add additional context in this case.
Is there ever a comma after ‘because’?
Normally, you shouldn’t place a comma after ‘because’. In most cases, there’s no reason to add one, and it’s incorrect to do so.
- This is because, the temperature was not set correctly.
The only time when you need a comma after ‘because’ is when it’s immediately followed by an interrupter – a phrase that interrupts the flow of the sentence to add some special qualification or emphasis. Such phrases are surrounded by commas.
When the ‘because’ clause comes first
‘Because’ is a subordinating conjunction. A clause introduced by it is a subordinate clause. That means that it can’t stand on its own but must be connected with an independent clause before or after it.
The previous sections discuss how to punctuate the subordinate (‘because’) clause when it comes after the independent clause. But when the ‘because’ clause comes first, a comma should always separate it from the following independent clause.
Note that it’s grammatically incorrect for a ‘because’ clause to stand on its own as a sentence. This creates a sentence fragment.
- We were unable to establish a causal relationship between the two variables. Because of the inherent limitations of the study design.
- Because of the inherent limitations of the study design, we were unable to establish a causal relationship between the two variables.
Worksheet: Comma before or after ‘because’
Want to test your understanding of when a comma is needed before (or after) ‘because’? Try completing the worksheet below. Add commas wherever you think they’re needed in the sentences given (there may be no commas needed in some cases).
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