A complex sentence has one independent clause and at least one dependent clause. The dependent clause can be an adverb clause, an adjective clause or a noun clause. Compare simple and compound sentences.
| Structure | Independent clauses | Dependent clauses | Example |
|---|---|---|---|
| simple | 1 | 0 | The rain stopped. |
| compound | 2 or more | 0 | The rain stopped, and the sun came out. |
| complex | 1 | 1 or more | When the rain stopped, the sun came out. |
| compound-complex | 2 or more | 1 or more | When the rain stopped, the sun came out, and we went outside. |
Key idea
Complex means the sentence has a dependent clause, not that it is long or hard to read.
Why it works
A complex sentence shows that one idea depends on another: the time, the reason, the condition. Mixing simple, compound and complex sentences makes writing flow and shows the reader how ideas connect.
Worked example: A clause inside a clause
What structure is “The book that you lent me was funny”?
- The independent clause is The book was funny.
- Inside it sits the adjective clause that you lent me, which can’t stand alone.
- One independent clause and one dependent clause.
Answer: complex
Worked example: Long but simple
What structure is “After a long day at the beach, the tired children fell asleep in the car”?
- Find subject–verb pairs: only children fell.
- After a long day, at the beach and in the car are phrases.
Answer: simple
Common mistake
Thinking complex means long or hard. “When it rained, we left” is short and complex; the long beach sentence above is simple. Count the clauses, not the words.