Compound-complex sentence
A compound-complex sentence contains at least two independent clauses and at least one dependent clause, so it both ranks one idea below another and sets two main ideas side by side.
Although the key was bent, the lock turned, and the door swung in on an empty hall.
Count the clauses. One dependent clause (although the key was bent), then two independent clauses joined by and. That combination is what the name describes: compound, because it has more than one main clause, and complex, because it has at least one dependent clause.
The four sentence types
Grammar sorts sentences by the clauses they contain:
- Simple: one independent clause. The lock turned.
- Compound: two or more independent clauses, joined by a conjunction such as and, but or so, or by a semicolon. The lock turned, and the door swung in.
- Complex: one independent clause plus at least one dependent clause. Although the key was bent, the lock turned.
- Compound-complex: two or more independent clauses plus at least one dependent clause.
Compound-complex sentence examples
The dependent clauses are in italics.
- When the power went out, we lit candles, and my brother told ghost stories.
- I wanted to call her, but I didn't, because I knew what she would say.
- The team that won last year lost in the first round, so the coach resigned.
- If you finish early, check your answers; the test is harder than it looks.
In the third example the dependent clause is a relative clause sitting inside the first main clause. It still counts.
How to identify one
Find every verb with its own subject. For each one, ask whether that clause could stand alone as a sentence. Two or more that can, plus one or more that cannot, means compound-complex. Watch for two verbs sharing one subject (She locked the door and left): that is one clause, not two.
Using it well
Some moments genuinely have this shape: a condition, a result and a consequence, all belonging to one breath. Broken into three sentences, the sequence would read as three separate events rather than one.
The risk grows with the length. The reader has to hold a subordinate idea while two main ideas resolve, and if the clauses are long, or the dependent clause is buried in the middle, they lose the thread. Two safeguards: keep the dependent clause at one end, and make sure the two main clauses are genuinely equal. If one is an afterthought, it belongs in a dependent clause too.
For a long sentence that grows by adding detail rather than clauses, see the cumulative sentence, which is easier to read at the same length.
Frequently asked questions
What is a compound-complex sentence?
It is a sentence with at least two independent clauses, which could each stand alone, and at least one dependent clause, which cannot. For example: 'Although the key was bent, the lock turned, and the door swung open.'
What is the difference between a compound sentence and a compound-complex sentence?
A compound sentence joins two or more independent clauses and has no dependent clause. Add one dependent clause, such as 'when the bell rang', and it becomes compound-complex.
How many clauses does a compound-complex sentence need?
At least three: two independent clauses and one dependent clause. It can have more of either.