Compound sentences
A compound sentence is a sentence made of two or more independent clauses, each with its own subject and verb, joined together as equals. The clauses are connected using a coordinating conjunction (such as "and", "but", "so"), a semicolon, or a semicolon with a conjunctive adverb (such as "however", "therefore").
Types of compound sentences
Joined with a coordinating conjunction
Two independent clauses linked by a comma plus one of the FANBOYS conjunctions (for, and, nor, but, or, yet, so).
e.g. I wanted to travel, but I had no money., She studied hard, so she passed the exam.
Joined with a semicolon
Two closely related independent clauses connected directly by a semicolon without a conjunction.
e.g. The weather improved; we decided to go hiking., He loves reading; she prefers watching films.
Joined with a semicolon and conjunctive adverb
Two independent clauses linked by a semicolon, a conjunctive adverb (however, therefore, moreover, meanwhile), and a comma.
e.g. The traffic was heavy; however, we arrived on time., Prices rose sharply; therefore, sales fell.
Joined with a colon
Used when the second clause explains, summarises or emphasises the first clause, both being independent.
e.g. She had one goal: she wanted to win., The plan was simple: everyone would contribute equally.
Rules to remember
- A compound sentence must contain at least two independent clauses, each able to stand alone as a complete sentence.
- When using a coordinating conjunction (FANBOYS), place a comma before it unless the clauses are very short.
- A semicolon can join two independent clauses only if they are closely related in meaning; do not use a comma alone (this causes a comma splice).
- When a conjunctive adverb (however, therefore, moreover) links clauses, it needs a semicolon before it and a comma after it.
- Do not confuse compound sentences with compound predicates, which have one subject sharing two verbs without a comma.
Examples in sentences
| Example | How it works |
|---|---|
| I enjoy studying English, and I also enjoy learning French. | Two independent clauses joined by comma + 'and'. |
| The exam was difficult, but most students still passed. | Comma + 'but' contrasts two complete ideas. |
| It started raining heavily; the match was cancelled. | Two related independent clauses joined by a semicolon alone. |
| He did not study for the test; therefore, he failed it. | Semicolon plus conjunctive adverb 'therefore' shows result. |
| She missed the bus, so she arrived late to work. | Comma + 'so' shows cause and effect between two clauses. |
| The company cut costs; nevertheless, profits declined. | Semicolon plus 'nevertheless' shows contrast between clauses. |
| We can eat at home, or we can go to a restaurant. | Comma + 'or' presents two independent alternatives. |
Common mistakes
Incorrect: I was tired, I went to bed early.
Correct: I was tired, so I went to bed early. (add a coordinating conjunction, or use a semicolon: I was tired; I went to bed early.)
Incorrect: She likes coffee, however he prefers tea.
Correct: She likes coffee; however, he prefers tea. (use a semicolon before 'however', not a comma)
Incorrect: He finished his homework and, watched television.
Correct: He finished his homework and watched television. (no comma needed here because this is a compound predicate, not a compound sentence, since both verbs share one subject)
Why this matters for IELTS
Using compound sentences accurately shows examiners that you can control coordination, one of the key structures assessed under Grammatical Range and Accuracy. Mixing coordinating conjunctions, semicolons and conjunctive adverbs correctly (rather than repeating "and" or writing comma splices) demonstrates sentence variety and precision, both in Writing Task 2 essays and in extended Speaking Part 2 and 3 answers, which can lift your band score noticeably.
Frequently asked questions
What is a compound sentence in simple terms?
It is a sentence built from two or more complete, independent clauses that are equally important and joined by a conjunction, semicolon, or colon.
What is the difference between a compound and a complex sentence?
A compound sentence joins two independent clauses of equal weight, while a complex sentence joins an independent clause with a dependent clause that cannot stand alone.
Can you start a compound sentence with a conjunction?
In formal writing it is best to keep coordinating conjunctions between the two clauses, but starting a sentence with 'And' or 'But' is acceptable in informal or stylistic writing.
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