What Is a Compound Sentence?

What Is a Compound Sentence?

A compound sentence is a sentence with at least two independent clauses and no dependent clauses. What’s an independent clause? It’s a phrase that can stand alone as a sentence. “I slept late” is an independent clause. So are “The sun is shining” and “Ella got a new dog.” Each has a subject and a verb and makes sense on its own. Examples of dependent clauses, which can’t be complete sentences on their own include: “whenever I go to the lake,” “how she got lost,” and “what makes him happy.” They don’t make sense on their own.

A compound sentence must contain at least two independent clauses. Here’s an example: “I practiced piano every day, yet I never got very good at it.” The two independent clauses are “I practiced piano every day” and “I never got very good at it.” They are joined by a comma and the coordinating conjunction “yet.” Both clauses have a subject and verb and make sense on their own, and since there are no dependent clauses, we know this is a compound sentence.

If a sentence contains only one independent clause, then it is a simple sentence, not a compound sentence. A sentence with three or more independent clauses (and no dependent clauses) is still a compound sentence, but once you begin adding in dependent clauses, it becomes a compound-complex sentence, which we discuss later on. Here is what a compound sentence example looks like diagrammed.

The sentence is: I went running, but Emily stayed inside.

The two independent clauses are each on their own line, and they’re connected by the coordinating conjunction “but.”

Different Types of Compound Sentences

Independent clauses can be joined in several ways to form compound sentences:

Coordinating Conjunction and a Comma

The most common way independent clauses in a compound sentence are linked is with a coordinating conjunction and a comma. There are seven coordinating conjunctions: for, and, nor, but, or, yet, so. (The acronym FANBOYS is often used to help remember them.) When you use one of these conjunctions to link the clauses, you must include a comma immediately before the conjunction.

Example: I ran the entire way there, but I still missed the bus.

Semicolon

Semicolons join two independent clauses without any joining words like conjunctions. Independent clauses separated by a semicolon could have been separated by a period and made into two separate sentences, but the author chose to keep the clauses linked in a single sentence.

Example: France is my favorite country to visit; I never run out of things to do there.

Colon

A colon is used to give more information about something mentioned in the preceding sentence. Be careful though; most of the phrases following a colon aren’t independent clauses, so it’s rare for a sentence with a colon to be a compound sentence.

Example: I learned my lesson: I can’t be trusted in Vegas.

Dash

Dashes can be used in place of colons or semicolons, and they’re used when the author wants to create a more abrupt stop or to emphasize the words after the dash. (Same with colons, be aware that most words that follow a dash aren’t an independent clause.)

Example: He wasn’t just late -- he didn’t show up at all.

What’s the Difference Between a Compound Sentence and a Complex Sentence?

As mentioned above, a compound sentence has at least two independent clauses. A complex sentence has one (and only one) independent clause and at least one dependent clause.

The sentence, “Ella got a new dog, and she’s going to bring it on Saturday” is a compound sentence because both “Ella got a new dog” and “she’s going to bring it on Saturday” are independent clauses. The sentence, “Before she went to the lake, Ella got a new dog,” is a complex sentence because “before she went to the lake” is a dependent clause, so that sentence only has one independent clause, not two.

Here are some examples of complex sentences.When the dependent clause occurs at the beginning of a sentence, it needs to be followed by a comma, but when the independent clause occurs at the beginning of a sentence, it isn’t followed by a comma.

“My brother was late because he forgot to feed the dog.”

• Even though “my brother was late” and “he forgot to feed the dog” are both independent clauses, this isn’t a compound sentence since “because,” the word that links them, isn’t a coordinating conjunction (it’s a subordinating conjunction). Therefore, “because” is included as part of the clause it’s in, and “because he forgot to feed the dog” is a dependent clause. Only coordinating conjunctions aren’t included in the clause they’re in when determining if a clause is independent or dependent.

“Whenever I hear his music, I start to cry.”

• “Whenever I hear his music” is the dependent clause

• "I start to cry" is the independent clause

“He has been very lonely since his best friend moved away.”

• “since his best friend moved away” is the dependent clause

• "He has been very lonely" is the independent clause

What Is a Compound-Complex Sentence?

What happens when a sentence contains more than two clauses? If it has at least two independent clauses and at least one dependent clause, it becomes a compound-complex sentence. (You might notice the compound-complex sentence requirements are just the requirements of a compound sentence and a complex sentence combined together).

Here are some compound-complex sentence examples. Note that each has at least two independent clauses and at least one dependent clause.

“I laughed when he fell in the mud, but then I felt sorry for him.”

“Whenever we get coffee, she shows up late, and it’s really starting to bother me.” “The restaurant is so expensive; I’ll have to save up money before we can go.”