Because vs. Because Of: What's the Difference?
Quick Answer
"Because" is a conjunction followed by a full clause with a subject and verb (because it was raining). "Because of" is a preposition followed by a noun, pronoun, or gerund (because of the rain). Both give a reason, but the grammar after each phrase is different, and mixing them up is one of the most common learner errors.
Difference at a Glance
| Feature | Because | Because of |
|---|---|---|
| Part of speech | Conjunction | Preposition |
| Followed by | A clause (subject + verb) | A noun / pronoun / gerund |
| Example | because it was cold | because of the cold |
| Typical position | Joins two clauses | Introduces a noun phrase |
Definitions
Because
A subordinating conjunction that introduces a reason clause.
because + subject + verb
"because it was raining"
"because she studied hard"
"because I forgot my keys"
Because of
A two-word preposition that introduces a noun, pronoun, or gerund.
because of + noun/gerund
"because of the rain"
"because of her hard work"
"because of forgetting my keys"
Grammar Rule
Key Rule: "Because" needs a clause (a subject and a verb) after it. "Because of" needs a noun, pronoun, or -ing form (gerund) after it — never a full clause.
A fast check: if what follows has its own verb, use "because". If what follows is just a thing, a name, or an -ing word acting like a noun, use "because of".
Common Mistakes
Incorrect: The game was cancelled because of it was raining.
Correct: The game was cancelled because it was raining.
"it was raining" is a clause, so it needs "because", not "because of".
Incorrect: She was late because the traffic.
Correct: She was late because of the traffic.
"the traffic" is a noun phrase, so it needs "because of".
Incorrect: He passed the exam because of he studied every day.
Correct: He passed the exam because he studied every day.
More Correct Examples
Mini Quiz
1. Choose the correct word: "The trip was cancelled _____ the storm."
Show answer and explanation
Answer: because of
"the storm" is a noun phrase, so it needs "because of".
2. Choose the correct word: "The trip was cancelled _____ a storm was approaching."
Show answer and explanation
Answer: because
"a storm was approaching" is a clause, so it needs "because".
3. Fix the sentence: "He failed the test because of he didn't study."
Show answer and explanation
Answer: He failed the test because he didn't study.
"he didn't study" is a clause, so "because of" must become "because".
Common Learner Questions
Is "because of" a preposition or two words joined together?
"Because of" functions as a single compound preposition. Grammatically it behaves exactly like other prepositions (such as "due to" or "owing to"): it must be followed by a noun, pronoun, or gerund, never by a full clause.
Can I start a sentence with "because"?
Yes. "Because it was late, we went home" is correct as long as the "because" clause is followed by a main clause. This is a common style myth — starting a sentence with "because" is grammatically fine.
What is the difference between "because of" and "due to"?
"Because of" and "due to" are used the same way grammatically (both need a noun after them), though traditional style guides prefer "due to" after a form of "to be" (the delay was due to rain) and "because of" elsewhere. In everyday and IELTS/TOEFL writing, both are widely accepted.