Four Sentence Structures: Simple, Compound, Complex, & Compound-Complex

Learn about English sentence structures

There are four sentence structures in English: Simple, Compound, Complex, and Compound-Complex. Here are examples of each:

  1. She ate lunch. (Simple: one independent clause)
  2. She ate lunch, but she was still hungry. (Compound: two independent clauses joined by a coordinating conjunction ).
  3. She was still hungry even though she had eaten lunch . (Complex: an independent clause + a dependent clause)
  4. She was tired, and she was still hungry even though she had eaten lunch (Compound-Complex: two independent clauses joined by a coordinating conjunction and one dependent clause)

First: Understanding Clauses

A clause is a group of words that includes a subject and a verb. It's important to understand that there are two types of clauses:

Independent Clauses

A sentence must have at least one independent clause. An independent clause is a group of words that form a complete thought when you put them together. Here are some examples:

These sentences are complete thoughts, which means that no more information is needed to understand them completely.

Dependent Clauses (Subordinate Clauses)

Dependent clauses are incomplete thoughts. They depend on an independent clause in order for the sentence to have meaning. Dependent clauses begin with a subordinate conjunction. Here are some examples:

As you can see, more information is needed. To create a complete sentence, you need to add an independent clause . Here are the examples again but written as complete sentences (known as complex sentences):

Now that you understand this, we can look at the four different sentence structures.

Structure #1: Simple Sentences

A simple sentence is one independent clause. A clause is a group of words that contain a subject and a verb, and an independent clause it a group of words that form a complete thought when you put them together. Here are some examples:

Again, all of these sentences are complete thoughts.

Structure #2: Compound Sentences

A compound sentence is made of two independent clauses joined by a coordinating conjunction .

Although the most commonly used coordinating conjunctions are but, and, so, and or, there are seven coordinating conjunctions in English:

[ independent clause ], [independent clause]
She ate lunch, but she was still hungry.
He sat down, and he read a book.
It was rainy, so we stayed inside.
We can order food or we can make pasta at home.

The above sentences are all independent clauses joined by a coordinating conjunction, so they are all compound sentences.

Structure #3: Complex Sentences

A complex sentence has a dependent clause and an independent clause. The dependent clause can come at the beginning of the sentence or at the end. Here are some examples:

(Note: When a dependent clause starts a sentence, you should put a comma at its end to show where the clause ends.)

An adjective clause (also known as a relative clause) is also considered a dependent clause as well. E.g.:

Structure #4: Compound-Complex

A compound-complex sentence has the following:

  1. two independent clauses joined a coordinating conjunction
  2. a dependent clause

The dependent clause can be anywhere in the sentence. Here are some examples:

Question: What about Compound-Compound? Complex-Complex?

Technically, you can make more complicated types of of sentence structures, for example:

Is this Compound-Compound-Compound sentence? No. It's still just called a Compound sentence. Also, it's a badly written sentence.

Is this a Complex-Complex sentence? No. It's still called a complex sentence, even though there are two dependent clauses.

Why is all this important? What sentence structures should I use?

Spoken English tends to mainly use simple and compound sentences, but higher-level writing (e.g. academic and business communications) should use some complex structures. A complex sentence can be more efficient because it can contain several ideas in the same sentence. Also, using conjunctions such although or because helps the reader understand how ideas relate to each other, which makes your writing more cohesive.

Still, w riting well doesn't mean only using long and complicated sentences. Writing is most effective when it's clear. This can be achieved by using short, simple sentences, such as this one. I n short, writing effectively and efficiently means using a variety of sentence structures.

^ By the way, the above two paragraphs contained the following: