Simple, Compound, Complex and Compound-Complex Sentences

Every sentence you write is built from clauses, and there are only four ways to combine them. Knowing the four sentence types will not make your writing correct on its own, but it gives you a set of tools for varying rhythm, showing how ideas relate and avoiding both choppy and tangled prose.

The building blocks: clauses

A clause is a group of words with a subject and a verb.

• An independent clause expresses a complete thought: The crowd cheered.
• A dependent clause begins with a subordinating word and needs an independent clause to complete it: when the final word was played.

Put them together and you get a complete sentence: The crowd cheered when the final word was played.

1. Simple sentences

A simple sentence has one independent clause. That does not mean it has to be short. It can have a compound subject, a compound verb and plenty of description:

• She won.
• My sister and her friend play Scrabble every Sunday afternoon.
• The old champion studied the board and quietly placed his tiles.

Each of these has just one subject-verb unit, even when the subject or verb is doubled.

Use it for: clear, emphatic statements. A short simple sentence after a long one has real punch.

2. Compound sentences

A compound sentence joins two or more independent clauses. You can connect them in three ways:

1. A comma plus a coordinating conjunction: She drew the Z, and her opponent groaned.
2. A semicolon: She drew the Z; her opponent groaned.
3. A semicolon plus a transition word: She drew the Z; consequently, her opponent groaned.

The seven coordinating conjunctions are for, and, nor, but, or, yet, so (FANBOYS). Each shows a different relationship, from addition (and) to contrast (but, yet) to result (so).

Use it for: ideas of equal weight. Compound sentences treat both halves as equally important.

3. Complex sentences

A complex sentence has one independent clause and at least one dependent clause. The dependent clause usually starts with a subordinating conjunction (because, although, since, when, while, if, unless, until, after, before) or a relative pronoun (who, which, that).

• Because the bag was empty, the game ended.
• The game ended because the bag was empty.
• The player who scored the bingo won the match.

Notice the comma rule: when the dependent clause comes first, put a comma after it. When it comes second, you usually do not need one.

Use it for: showing which idea matters more. The independent clause carries the main point; the dependent clause gives the reason, condition, time or contrast.

4. Compound-complex sentences

A compound-complex sentence has at least two independent clauses and at least one dependent clause:

• Although the rack was terrible, she found a seven-letter word, and the room went silent.

Here although the rack was terrible is dependent, while she found a seven-letter word and the room went silent are both independent.

Use it for: rich, connected ideas. Use these sparingly, though; too many in a row make writing hard to follow.

Quick identification guide

To classify any sentence, first underline each subject-verb pair, then ask whether each clause could stand alone.

Why variety matters

Read this paragraph:

I played a word. It scored twenty points. My friend played next. She scored thirty.

Every sentence is simple, so it sounds robotic. Now compare:

I played a word that scored twenty points, but my friend replied with thirty.

Combining clauses shows how the events relate: the second play was a response to the first. Good writers mix all four types, using simple sentences for emphasis and complex ones to explain connections.

Study the joining words

The flashcards below cover all seven coordinating conjunctions and five common subordinating ones. Say the type out loud before you flip each card, then read the example to see it in a sentence.

Practice quiz