Compound Sentences: Definition, Rules and 30 Examples

A compound sentence is one of the most useful tools in written and spoken English, yet many learners use it incorrectly without realising. Once you understand the compound sentence definition and the three rules that govern it, your writing becomes more varied, more fluent, and easier to read.

What Is a Compound Sentence?

A compound sentence is a sentence that contains two or more independent clauses joined together. An independent clause is a group of words with a subject and a verb that expresses a complete thought on its own.

The word compound simply means "made of more than one part." In grammar, that means taking two complete sentences and connecting them so they share a single sentence structure.

Example:

• Clause 1: She was tired.
• Clause 2: She kept working.
• Compound sentence: She was tired, but she kept working.

Both clauses are still complete thoughts. The conjunction but shows the contrast between them.

The Three Ways to Form a Compound Sentence

There are exactly three grammatically correct methods. Each produces a valid compound sentence; the choice depends on the relationship between the ideas and the rhythm you want.

Method 1: Comma and a Coordinating Conjunction (FANBOYS)

This is the most common method. Place a comma before the coordinating conjunction.

The seven coordinating conjunctions spell the acronym FANBOYS:

Method 2: Semicolon Alone

When the two clauses are closely related and the connection is obvious, a semicolon can replace the comma and conjunction entirely.

The interview went well; she received an offer the next day.

Understanding when to use a semicolon versus a comma is a common source of confusion. For a full breakdown of that decision, see our guide on comma vs semicolon usage.

Method 3: Semicolon with a Conjunctive Adverb

A conjunctive adverb (also called a transitional adverb) can follow a semicolon to show the relationship more explicitly. A comma follows the conjunctive adverb.

Common conjunctive adverbs: however, therefore, moreover, consequently, otherwise, nonetheless, meanwhile.

The deadline was approaching; therefore, the team worked through the evening.

30 Compound Sentence Examples Sorted by Conjunction

The examples below are organised by conjunction so you can see how each one changes the meaning.

For (reason)

1. She took the later train, for the first one was fully booked.
2. He apologised, for he knew he had been wrong.
3. They rested early, for the climb would begin at dawn.
4. I kept the receipt, for the item might need returning.

And (addition)

5. The children played outside, and their parents relaxed in the garden.
6. She submitted the report, and her manager approved it immediately.
7. He cooked a large meal, and everyone asked for second helpings.
8. We packed our bags, and the taxi arrived exactly on time.

Nor (negative addition)

9. He did not apologise, nor did he offer any explanation.
10. She cannot cook well, nor can she follow a simple recipe.
11. They did not complain, nor did they ask for a refund.

But (contrast)

12. The hotel was expensive, but the service was outstanding.
13. He practised every day, but his pronunciation did not improve.
14. The weather was grey, but the city looked beautiful.
15. She wanted to help, but she did not know how.

Or (alternative)

16. You can pay by card, or you can use the mobile app.
17. We could leave now, or we could wait for the others.
18. She will accept the role, or she will look for another position.

Yet (unexpected contrast)

19. The question looked easy, yet most students answered it incorrectly.
20. He had little experience, yet he performed better than the veterans.
21. The bag was heavy, yet she carried it without complaint.

So (result)

22. The printer was out of paper, so I used a different machine.
23. She studied hard for months, so the result did not surprise her.
24. The road was flooded, so we took an alternative route.
25. He forgot his umbrella, so he arrived completely soaked.

Semicolon (no conjunction)

26. The flight was delayed by four hours; we used the time to explore the terminal.
27. Her argument was clear and well-structured; the audience listened in silence.
28. The match ended in a draw; neither team deserved to lose.

Semicolon and Conjunctive Adverb

29. The budget had been cut; however, the project continued as planned.
30. She had never visited the city before; nonetheless, she navigated it with confidence.

The Most Common Error: The Comma Splice

A comma splice is the mistake of joining two independent clauses with only a comma and no conjunction.

Incorrect: I was late, the meeting had already started.

A comma alone is not strong enough to join two independent clauses. Fix it by adding a coordinating conjunction, by using a semicolon, or by splitting the clauses into two separate sentences.

Correct: I was late, so the meeting had already started. Correct: I was late; the meeting had already started. Correct: I was late. The meeting had already started.

Knowing how sentences are built from the inside out helps you avoid this kind of error. A solid grounding in English sentence structure makes it easier to spot where one clause ends and another begins, which is exactly the judgment a comma splice gets wrong.

Simple or Compound? A Quick Quiz

Read each sentence and decide whether it is simple or compound. Answers are below.

1. The student opened her laptop and started the test.
2. The film was long, but the story kept us engaged.
3. Running every morning is her favourite habit.
4. He booked the flights; his partner arranged the hotels.
5. She and her colleague both attended the conference.

Answers:

1. Simple. "And" connects two verbs (opened and started), not two independent clauses. There is only one subject.
2. Compound. Two independent clauses joined by but.
3. Simple. One subject (running every morning), one verb (is).
4. Compound. Two independent clauses joined by a semicolon.
5. Simple. Two subjects share one verb (attended). There is no second independent clause.

The distinction matters because linking words and conjunctions work differently depending on the sentence type.

Compound vs. Other Sentence Types

It helps to see compound sentences alongside the other main types:

Simple sentences keep things clear; compound sentences show relationships between ideas; complex sentences handle cause, condition, and contrast; compound-complex sentences do all of the above at once. A text built on only one type starts to feel mechanical. Mix them.

Conclusion

A compound sentence joins two independent clauses using one of three methods: a comma and a coordinating conjunction (FANBOYS), a semicolon alone, or a semicolon followed by a conjunctive adverb. A few things to keep in mind:

• Each clause in a compound sentence must be able to stand alone as a complete thought.
• A comma without a conjunction between two independent clauses is a comma splice, which is a grammatical error.
• The seven coordinating conjunctions (FANBOYS) each express a different logical relationship.
• A semicolon can replace the comma and conjunction when the connection is clear.
• Mixing compound sentences with simple, complex, and compound-complex sentences makes writing more fluid and natural.

Want to see how confidently you apply these structures in real English? Take our English level test, which takes about 30 minutes and covers grammar, vocabulary, and comprehension across all CEFR levels.