Conjunction vs Preposition: The 2-Second Test

The main difference between conjunction and preposition is this: conjunctions link clauses or words, while prepositions head a phrase that takes a noun, pronoun, or gerund. In practice: use conjunctions when a full subject + finite verb clause follows to join ideas (cause, time, contrast)—e.g., because it rained; before we left. Use prepositions to show relationships of time/place/cause/purpose with a noun phrase—e.g., because of the rain; before dinner; during the meeting. If you’re unsure, the 2-second test below will keep you safe in exams and at work.

Use this quick diagnostic to decide instantly: if a subject + finite verb follows → conjunction; if a noun/pronoun/gerund follows → preposition. This page gives you the fast rule, a side-by-side table for the tricky words, a short quiz, and a printable cheat sheet.

Words that switch roles (side-by-side table)

Same word, different job—depending on what follows.

Quick decision tree

• Does a subject + finite verb follow? → It’s a conjunction.
• Otherwise, is it followed by a noun/pronoun/gerund? → It’s a preposition.
• Unsure or in exams? Prefer least-controversial forms: than I am; because + clause.

Common errors & instant fixes

• because vs because of → ❌ because of it rained → ✅ because it rained / ✅ because of the rain
• during is preposition-only → ✅ during the meeting ; ❌ during I was speaking
• despite / in spite of are prepositions → ✅ despite the delay ; ❌ despite it was late
• for as conjunction means “because” and links two independent clauses: We left, for the roads were closed.

Reassurance: you’re not alone

1-minute quiz (8 items)

Decide if the bold word is a Preposition or a Conjunction. Click to reveal the answer.

• I waited **until** 6.

  Answer: Preposition — apply the 2-second test.
• I waited **until** the gates opened.

  Answer: Conjunction — apply the 2-second test.
• She spoke **as** a volunteer.

  Answer: Preposition — apply the 2-second test.
• We left, **for** the team was tired.

  Answer: Conjunction — apply the 2-second test.
• We met **after** class.

  Answer: Preposition — apply the 2-second test.
• We met **after** we finished.

  Answer: Conjunction — apply the 2-second test.
• They succeeded **because of** teamwork.

  Answer: Preposition — apply the 2-second test.
• They succeeded **because** they planned well.

  Answer: Conjunction — apply the 2-second test.

Google FAQs (PAAs) answered

Are conjunctions and prepositions the same?

No. Prepositions head a phrase that takes a noun/pronoun/gerund; conjunctions link clauses/words. Some items can be either, depending on what follows.

What is an example of a preposition and a conjunction?

Preposition: We waited before the show.
Conjunction: We left before the show started.

How do you know if for is a preposition or conjunction?

If for is followed by a noun/gerund (for you; for coming) → preposition. If it links two independent clauses and means “because,” usually with a comma (We left, for the roads were closed) → one of the Coordinating conjunctions.

What are 10 examples of the preposition to?

1. We walked to the park.
2. Please give it to me.
3. The key to the house is missing.
4. I’m used to cold weather.
5. She confessed to the crime.
6. They contributed to the project.
7. I look forward to meeting you.
8. Access to the library is restricted.
9. The road to Kathmandu is closed.
10. We’ll go to your place after dinner.

Myth-busters (style vs grammar)

• “Due to” is wrong. → Modern usage accepts it widely; some styles still prefer because of in certain structures. Know your audience.
• “Like” can’t be followed by a clause. → In formal writing prefer as for full clauses; informally, like + clause occurs but may be marked down in exams.
• “While” is a preposition. → It isn’t; it’s a conjunction. (A while is a noun phrase.)

Printable cheat sheet (1 page)

Everything on one page: the 2-second test, the side-by-side table, eight paired examples, and six error-fixes. Print this section or save as PDF in your browser.

• Test: clause → conjunction; noun/gerund → preposition.
• Pairs: before/after/since/until; because vs because of; like vs as; than (I/me).
• Fixes: ❌ because of it rained → ✅ because it rained; ❌ despite it was → ✅ despite the delay.

Further study & related reading

• Linking Words overview
• Transition words (types, punctuation, long lists)
• Prepositions (core guide)
• Conjunctions (incl. Coordinating conjunctions)
• transition words for contrast (when you need adverbial transitions rather than conjunctions/prepositions)