Because is one of the most useful words for explaining reasons. It links a cause to an effect, and it can appear in the middle of a sentence or at the start. This page gives examples, covers the comma rules and answers common questions, such as whether because can be a full sentence.
What Does “Because” Do?
Because is a subordinating conjunction. That means it introduces a dependent clause, a group of words with a subject and a verb that cannot stand alone, and attaches it to a main clause.
- main clause: We stayed home
- because clause: because it was raining
Together: We stayed home because it was raining.
The because clause answers the question why?. To state a purpose rather than a reason, see the negative infinitive of purpose.
Because Sentences Examples
With “because” in the middle
When the main clause comes first, you usually do not need a comma before because.
- We rode the bus because it was cheaper.
- I stayed home because it was raining.
- She passed the exam because she studied hard.
- He didn’t call you because he lost his phone.
- The children were quiet because the film had started.
With “because” at the start
When the because clause comes first, put a comma after it.
- Because I was happy, I smiled.
- Because she was tired, she went to bed early.
- Because the traffic was bad, we missed the movie.
- Because the shop was closed, they ate at home.
Either order is fine. Starting with because puts more weight on the reason.
Because vs. Because Of
These two forms look alike but follow different patterns:
- because + clause (subject and verb)
- because of + noun, pronoun or noun phrase
| Because | Because of |
|---|---|
| We cancelled the trip because it was raining. | We cancelled the trip because of the rain. |
| He sat down because he felt dizzy. | He sat down because of dizziness. |
| I was late because the traffic was heavy. | I was late because of the traffic. |
A quick test: if what follows contains a verb with its own subject, use because. If it is just a noun phrase, use because of.
Can “Because” Be a Full Sentence?
A group of words beginning with because and containing a subject and verb is still a dependent clause. On its own, it is a sentence fragment:
- Incorrect: Because the bus was late.
- Correct: Because the bus was late, we missed the first class.
- Correct: We missed the first class because the bus was late.
There are exceptions in speech and informal writing. In dialogue, Because can be a complete reply to a why question:
“Why did you leave?” “Because.”
This works because the context supplies the rest, and it often signals refusal to explain. In formal writing, a fragment starting with because is usually treated as an error unless it is used deliberately, as in fiction. If you are practising fragment fixes, try the sentence correction exercises.
Can You Use More Than One “Because” in a Sentence?
Yes, as long as the sentence stays clear. You can join several reasons:
- Because the storm was coming, because the road was closed, and because we were tired, we stopped for the night.
- We chose the cottage because it was cheap and because it was close to the sea.
Too many can make a sentence heavy. If you use three or more, consider splitting the sentence or using a list of reasons in separate sentences.
Common Mistakes
- Fragments: leaving a because clause alone. Attach it to a main clause.
- Comma before a mid-sentence because: usually unnecessary. I stayed home, because it was raining is often marked as over-punctuated, though a comma is sometimes used for a deliberate pause or when the reason is an afterthought.
- Because of + clause: We stayed in because of it was raining is wrong. Say because it was raining or because of the rain.
- “The reason is because”: many style guides prefer The reason is that… since reason and because repeat each other.
- Informal noun use: phrases like “because science” are casual online style and best avoided in formal writing.
Another quick check is whether your sentence has a complete subject and verb in the main clause. Without them, the whole sentence is a fragment.
Practice and Answers
Fill in because or because of.
- We cancelled the match ______ the rain.
- He sat down ______ he was feeling dizzy.
- They were late ______ the traffic.
- We hurried indoors ______ it was raining.
Fix the fragment: Because I forgot my keys.
Answers: 1. because of; 2. because; 3. because of; 4. because. Fragment fix: Because I forgot my keys, I waited outside. or I waited outside because I forgot my keys.