Compound Sentences in English: Rules & Examples

A compound sentence is made up of two or more independent clauses — groups of words that each contain a subject and a verb and can each stand alone as a complete sentence. The clauses are linked by a coordinating conjunction (such as and, but or so) preceded by a comma, or by a semicolon alone. I wanted coffee, but the café was closed. is a classic compound sentence: two complete thoughts joined to show contrast. Building accurate compound sentences is a core B1 skill on the CEFR scale.

Compound sentences are one of the four sentence types in English (simple, compound, complex and compound-complex). Using them well helps you avoid a string of short, choppy simple sentences and shows a reader how your ideas relate to each other — whether the relationship is addition, contrast, cause and result, or choice.

How to Form a Compound Sentence

There are two main ways to join independent clauses into a compound sentence:

Structure	Example	Notes
Clause + , + FANBOYS + Clause	I wanted coffee, but the café was closed.	Always place a comma before the conjunction when joining two independent clauses.
Clause + ; + Clause	She studied hard; she passed the exam.	Use a semicolon when the ideas are closely related and no conjunction is needed. No capital letter after the semicolon.
Clause + ; + conjunctive adverb + , + Clause	He was tired; however, he kept working.	Words like however, therefore and moreover are not coordinating conjunctions — they need a semicolon before them and a comma after.

The FANBOYS Conjunctions in Detail

Each coordinating conjunction has a specific meaning. Choosing the right one is key to expressing your idea clearly.

Conjunction	Meaning	Example
for	reason (because)	She left early, for she had a long drive ahead.
and	addition	I made dinner, and he washed the dishes.
nor	negative addition	She did not call, nor did she send a message.
but	contrast	I wanted coffee, but the café was closed.
or	alternative / choice	You can stay here, or you can come with us.
yet	contrast (despite this)	The film was long, yet I enjoyed every minute.
so	result / consequence	It was raining, so we took a taxi.

Compound Sentences with a Semicolon

When two independent clauses are closely related in meaning, you can join them with a semicolon instead of a conjunction. The semicolon signals that the ideas belong together without spelling out the exact relationship.

• She studied hard; she passed the exam. (The result follows naturally from the effort.)
• The sun set; the city began to glow. (A sequence of closely linked events.)
• Tom loves jazz; his sister prefers classical music. (Contrast without but.)

Note that a comma alone between two independent clauses — without a conjunction — creates a comma splice, which is a common error. Use either a coordinating conjunction after the comma, a semicolon, or a full stop.

Formation Examples at a Glance

• Clause + FANBOYS + Clause: The alarm rang, and she jumped out of bed.
• Clause + FANBOYS + Clause: He worked all night, so he finished the report on time.
• Clause + semicolon + Clause: The meeting ended at noon; everyone went to lunch.
• Clause + semicolon + conjunctive adverb + , + Clause: The price was high; however, the quality was excellent.

Common Mistakes

• Comma splice — missing conjunction:
  Wrong: I was hungry, I ordered a pizza.
  Correct: I was hungry, so I ordered a pizza. or I was hungry; I ordered a pizza.
• No comma before the conjunction:
  Wrong: She wanted to stay but she had to leave.
  Correct: She wanted to stay, but she had to leave.
• Using a conjunctive adverb as a coordinating conjunction:
  Wrong: It was cold, however we went for a walk.
  Correct: It was cold; however, we went for a walk.
• Joining a dependent clause to an independent clause and calling it compound:
  Wrong label: Because it rained, we stayed inside. (This is a complex sentence, not compound.)
  A compound sentence requires two independent clauses. Because it rained cannot stand alone.

Practice Tips

• Write two simple sentences, then combine them. Take any pair of related simple sentences and practise joining them with each FANBOYS conjunction. Notice how the meaning shifts depending on which conjunction you choose.
• Read your writing aloud. If you hear a long run-on sentence, look for a natural pause — that is often the right place for a comma + conjunction or a semicolon.
• Vary between conjunctions and semicolons. Using only and to join clauses can make writing feel monotonous. Mix in but, so, yet and the occasional semicolon for variety.
• Check every comma. Before a conjunction linking two independent clauses, a comma is required. Before a conjunction linking two words or phrases (not full clauses), no comma is needed: She sang and danced (no comma) vs. She sang, and the audience danced (comma).

Practice Exercises

Explore related grammar topics:

All Grammar Topics Complex Sentences Conjunctions Clauses Punctuation

Frequently Asked Questions

What is a compound sentence?

A compound sentence is made up of two or more independent clauses joined by a coordinating conjunction (for, and, nor, but, or, yet, so) preceded by a comma, or by a semicolon alone. Each clause has its own subject and verb and could stand alone as a complete sentence. Example: I wanted coffee, but the café was closed.

What are the FANBOYS conjunctions?

FANBOYS is a helpful acronym for the seven coordinating conjunctions in English: For (reason), And (addition), Nor (negative addition), But (contrast), Or (alternative), Yet (contrast despite), So (result). Each one joins two independent clauses and signals a different logical relationship between them.

Do you always need a comma before a coordinating conjunction?

You need a comma before a coordinating conjunction only when it joins two independent clauses in a compound sentence: She was tired, so she went to bed. If the conjunction joins two words, phrases or dependent clauses — not two full independent clauses — no comma is needed: She sang and danced (no comma). The key test is whether each part could stand alone as a complete sentence.

When should I use a semicolon instead of a conjunction?

Use a semicolon when two independent clauses are closely related in meaning and the relationship is clear without a conjunction: She studied hard; she passed the exam. A semicolon is also used before conjunctive adverbs such as however, therefore and moreover, which must be followed by a comma: It was cold; however, we went for a walk.

What is a comma splice and how do I fix it?

A comma splice happens when two independent clauses are joined by a comma alone, without a coordinating conjunction: I was hungry, I ordered a pizza. Fix it by adding a conjunction after the comma (I was hungry, so I ordered a pizza), replacing the comma with a semicolon (I was hungry; I ordered a pizza), or splitting them into two sentences.

What is the difference between a compound sentence and a complex sentence?

A compound sentence joins two or more independent clauses with a coordinating conjunction or semicolon: It rained, so we stayed inside. A complex sentence joins an independent clause with at least one dependent (subordinate) clause using a subordinating conjunction such as because, although or when: Because it rained, we stayed inside. The dependent clause in a complex sentence cannot stand alone.

Can a compound sentence have more than two independent clauses?

Yes. You can join three or more independent clauses in one compound sentence. When listing clauses, place a comma after each one and add the conjunction before the last: I packed my bag, I locked the door, and I headed for the station. Be careful not to create an overly long sentence that becomes hard to follow — splitting into two compound sentences is often clearer.

How is ‘yet’ different from ‘but’ as a conjunction?

Both yet and but express contrast, but yet carries a slightly stronger sense of surprise or unexpectedness: The task was difficult, yet he completed it in an hour suggests the result is more surprising than The task was difficult, but he completed it. In formal writing, yet can sound more emphatic. In everyday speech, but is far more common.

Is ‘however’ a coordinating conjunction?

No. However, therefore, moreover, nevertheless and similar words are conjunctive adverbs, not coordinating conjunctions. They cannot join two independent clauses with just a comma. You must use a semicolon before them and a comma after: The price was high; however, the quality was excellent. Using only a comma before however creates a comma splice.

At what level are compound sentences taught?

The basics of compound sentences — joining clauses with and, but and so — are introduced at A2 to B1 on the CEFR scale. The full set of FANBOYS conjunctions, semicolons and awareness of comma splices are typically consolidated at B1. Understanding conjunctive adverbs like however and therefore is a B2 skill. Mastering all compound sentence structures improves clarity in writing exams such as IELTS and Cambridge B2 First.