What makes someone a “good” writer? While there are lots of answers to that question, one thing most great writers do is vary their sentence structure. They mix long, flowing sentences with short, powerful ones to communicate their points.
But don’t worry: you can learn to do this, too! It starts with understanding different types of sentences and their structures. One type of sentence you’ve probably heard of that can add variety and depth to your writing is a complex sentence. But what are complex sentences, exactly?
We’re here to help you understand exactly what complex sentences are and why they’re important by covering the following in this article:
- Answering the question, “What is a complex sentence?”
- Discussing when to use complex sentences
- Reviewing the different parts of complex sentences
- Explaining the difference between complex sentences, compound sentences, and compound-complex sentences
Ready to become a complex sentence wizard? Then let's get started!
What Is A Complex Sentence?
Here’s a pretty straightforward complex sentence definition: a complex sentence is made up of two clauses, one independent clause and at least one dependent clause.
And that’s it! That’s the definition of a complex sentence. But it’s probably pretty obvious that in order to write complex sentences of your own, you need to understand what a clause is. A clause is a part of a sentence that contains a subject and a verb. The subject is the person or entity taking action in the clause, and the verb is the action that the subject is taking. These clauses fall into two category types: independent clauses and dependent clauses.
Both independent clauses and dependent clauses--the types of clauses that make up complex sentences--have a subject and a verb. But how do you know when you’re dealing with an independent clause vs. a dependent clause? Here’s the difference between the two: an independent clause can stand alone as a sentence, and a dependent clause cannot stand alone as a sentence.
In other words, if you broke up a complex sentence into its individual clauses, the independent clause could make a new sentence all by itself. Here are some examples of complex sentences where we’ve bolded the independent clause.
Independent Clause #1: Because she was late for school, Cora has detention this afternoon.
Independent Clause #2: We’re definitely going to the Lizzo concert even though it’s supposed to rain.
See how the bold part of the sentence, i.e. the independent clause, can make a sentence all by itself?
But if you tried to make the dependent clause into its own sentence, it wouldn’t make any sense on its own. Take a look at the not bolded sections of the sentences above. If you walked up to your friend and said “Because she was late for school,” your friend would have no idea what you were talking about! That’s because you need an independent clause to understand what a dependent clause means. In other words, dependent clauses rely on independent clauses in order to make sense!
Dependent clauses don’t make sense on their own because they begin with something called a subordinating conjunction that subordinates, or makes the clause dependent on the independent clause. Here’s a list of subordinating conjunctions to help you identify where a dependent clause begins in a complex sentence:
Now, let’s take a look at some of those subordinating conjunctions in action. In the examples below, we’ve put the dependent clause in bold and underlined the subordinating conjunction:
Dependent Clause #1: After the store closed, the manager locked the doors.
Dependent Clause #2: They checked for an oil leak before they started the car.
Dependent Clause #3: Even though they waited for an hour, their food never came.
See how the subordinating conjunction helps us find the dependent clauses? Knowing what to look for makes finding a dependent clause a lot easier.
Independent Clauses + Dependent Clauses = Complex Sentences
Thee three examples above also show us how dependent clauses need to be paired with independent clauses for them to make sense. The independent clauses (which aren’t bolded) reveal what happened after the store closed, what they did or what happened before they started the car, and what did or didn’t happen even though they waited for an hour.
And that’s why dependent clauses can’t stand alone--they need an independent clause to go with them in order to form a complete thought, which creates a complex sentence!
We’re going to look at more examples of dependent clauses, independent clauses, and how they come together to form complex sentences in a bit, but let’s talk about when to use complex sentences first.
When to Use Complex Sentences
Maybe you aren’t sure when it’s appropriate or necessary to use a complex sentence in your own writing. One way to decide when to use a complex sentence is to think about what meaning or information you want to convey.
When you use simple sentences, it’s difficult to convey much more information than a single action that a single subject took. But when you use complex sentences, you can convey cause and effect, the progression of events, and other critical information. You can also use complex sentences to elaborate on a claim, compare and contrast ideas, and combine ideas that are similar into one point. You can see how a complex sentence can add clarity that a simple sentence can’t in this example:
Simple Sentence: I’m going swimming!
Complex Sentence: I’m going swimming even though there are sharks in the water!
Another reason to use complex sentences is sentence variety, which is one way you can take your writing to the next level. Sentence variety is when you use different types of sentence structures in your writing in a strategic, intentional way. A piece of writing that is made up of varied sentence structures can be much more engaging for people to read. Writing that doesn’t strategically use a variety of sentences can often strike readers as boring and monotonous, and no writer wants that!
Here’s an example of a paragraph that doesn’t have sentence variety. This paragraph is only made up of simple sentences, which consist of a subject, a verb, and a predicate. These three elements come together to create one independent clause:
I went to the store on Thursday. I bought chips and salsa. I drove home. I ate the chips and salsa. I watched TV. I got tired at midnight. I went to bed.
You see how robotic and choppy that paragraph is? That’s because it’s made up of one type of sentence only--simple sentences. Creating sentence variety by incorporating some complex sentences could help this paragraph have better flow, and someone reading this paragraph would be less likely to get frustrated or bored.
The example paragraph above would sound a bit different if the writer incorporated complex sentences. Here’s what the paragraph above could sound like if some of the simple sentences were rewritten as complex sentences:
I went to the store on Thursday because I wanted to buy some chips and salsa. After I drove home, I ate the chips and salsa. I watched TV until I got tired at midnight. I went to bed.
Incorporating complex sentences lets you combine similar ideas, express cause and effect, and clarify ideas by adding important details. And as an added bonus: complex sentences make this paragraph much more pleasant to read.
Just remember: if you aren’t sure when to use complex sentences, just think about what type of writing you’re doing, what your goals are for your writing, and check what you’ve already written for sentence variety. That should help you decide when it could be effective to incorporate a complex sentence!
3 Complex Sentence Examples
Let’s look at three complex sentence examples to help you get a better idea of what a complex sentence looks like, what the parts of a complex sentence are, and how to break down complex sentences into their parts so you can identify them on your own in the future!
Example #1: Independent Clause, Dependent Clause
While complex sentences must have one independent clause and at least one dependent clause, the clauses can go in any order. Here’s an example of a complex sentence where the independent clause comes first, and the dependent clause comes second:
I didn’t go to the store because I already had chips and salsa at home.
Can you tell that there are two clauses in that sentence, and where one clause ends and the next begins? Let’s break the sentence down into the independent clause and the dependent clause:
Independent clause: I didn’t go to the store
Dependent clause: because I already had chips and salsa at home.
The independent clause--I didn’t go to the store-- can stand alone as a sentence because it forms a complete thought. The dependent clause--because I already had chips and salsa at home--can’t stand alone as a sentence. It doesn’t form a complete thought!
Also note that there isn’t a comma before the subordinating conjunction. In most instances, you don’t need to separate a dependent clause with a comma when it comes after an independent clause!
Example #2: Dependent Clause, Independent Clause
Next, we’ll look at a second complex sentence where the dependent clause comes first, and the independent clause comes second. This type of complex sentence is called a periodic sentence--a sentence where the essential information doesn’t come until the end of the sentence.
Complex sentences that place the essential information at the end of the sentence can create a sense of suspense in your writing! We’ll use the same sentence from above so you can get an idea of how you can rewrite sentences for sentence variety:
Because I already had chips and salsa at home, I didn’t go to the store.
You already know which clause is the dependent clause--because I already had chips and salsa at home--and which clause is the independent clause--I didn’t go to the store. But do you see how the clauses in complex sentences can be rearranged and the sentence still makes sense? This is something to keep in mind when you’re trying to add variety to your writing: you can move the clauses around in complex sentences!
One last tip: when a dependent clause comes before an independent clause, you separate them with a comma.
Example #3: Two Dependent Clauses
We’ve looked at two similar complex sentence examples, so now let’s look at a third example that’s a little bit different from the first two:
Even though I was nervous about the date, I had a really great time after we started talking.
We know this is a complex sentence because it’s made up of a dependent clause and an independent clause. But this complex sentence has two dependent clauses. Let’s break this complex sentence down into its three clauses so we’re on the same page:
Dependent clause: Even though I was nervous about the date,
Independent clause: I had a really great time
Dependent clause: after we started talking.
Some complex sentences include multiple dependent clauses to add more context to the essential information conveyed by the independent clause, like in the example above!
Now let’s talk about how to use those commas. Remember: complex sentences that begin with a dependent clause need a comma between the dependent and independent clauses, and sentences that begin with an independent clause don’t need a comma separating the independent clause and the dependent clause.
In this case, we need to use both comma rules. To make this grammatically correct, we need to add a comma after the first dependent clause (since it comes before the independent one). We don’t need a comma between the independent clause and the second dependent clause since the dependent clause comes second!
Now that we’ve talked through complex sentences and looked at some complex sentence examples, let’s discuss the difference between two types of sentences that are commonly confused with each other: compound sentences and complex sentences.
Compound Vs. Complex Sentences: What’s the Difference?
Complex sentences are sometimes confused with compound sentences, but they aren’t the same thing! We defined complex sentences as sentences that are made up of an independent clause and a dependent clause, but what’s a compound sentence?
A compound sentence is made up of at least two independent clauses that are joined by a coordinating conjunction (remember that for, and, nor, but, or, yet, and so are coordinating conjunctions). Unlike complex sentences, compound sentences don’t have a dependent clause. And, unlike complex sentences, the two clauses that make up a compound sentence can be separated and made into their own, stand-alone sentences.
Put another way, you could also describe compound sentences as being made up of two simple sentences.
Let’s look at a couple of examples of compound sentences so you can see how they’re different from complex sentences! Here’s one example of a compound sentence:
I cooked dinner, but I didn’t set the table.
The sentence above is a compound sentence because it’s made up of the following independent clauses:
Independent Clause #1: I cooked dinner,
Independent Clause #2: but I didn’t set the table.
Each of those clauses could stand alone as simple sentences, right? Both clauses also convey information that is essential to understanding the full meaning of the sentence. They’re also separated by the coordinating conjunction, “but.”
Though the independent clauses in compound sentences are often separated by a comma and coordinating conjunction, the clauses in a compound sentence can also be separated by a semicolon, which means that there’s no need for a coordinating conjunction.
Here’s an example of a compound sentence with independent clauses separated by a semicolon:
The cat ran away; the children were devastated.
Just like in the first example of a compound sentence, the two (really sad!) independent clauses in the sentence above can function as sentences by themselves. They’re just separated by a semicolon instead of a comma and coordinating conjunction.
So, to tell the difference between complex and compound sentences, you just need to remember that a complex sentence is made up of an independent and a dependent clause, and a compound sentence is made up of independent clauses and no dependent clauses!
Next, we’ll look at another type of complex sentence: the compound-complex sentence.
What Compound-Complex Sentences Are (And When to Use Them)
In addition to complex sentences and compound sentences, there are also compound-complex sentences. Since this type of sentence is named after both compound and complex sentences, it makes sense that a compound-complex sentence would combine some of the characteristics of complex and compound sentences, right? That’s pretty much exactly what it does!
A compound-complex sentence is made up of two or more independent clauses (like a compound sentence) and one or more dependent clauses (like a complex sentence).
Since compound-complex sentences combine some of the components of complex sentences and compound sentences, you might be wondering whether compound-complex sentences count as complex sentences and as compound sentences. Technically, yes! Since compound-complex sentences include all of the minimum clauses required to make a complex sentence and a compound sentence, you could say that compound-complex sentences count as both. But compound-complex sentences go above and beyond the required components of compound and complex sentences, so that’s why they need to be called by their proper name: compound-complex sentences.
Since compound-complex sentences contain more clauses and types of clauses, they’re a more sophisticated type of sentence. You can use compound-complex sentences to add greater complexity and depth to your writing style. Compound-complex sentences really allow you to infuse your writing with detail and context, like explaining when something happened, why it happened, and/or how it happened.
Because you can include multiple independent and dependent clauses in compound-complex sentences, you’re able to give your reader even more essential and supplementary information about a scenario or story in a single sentence. This can be an important tool for making sure your readers understand what you’re trying to say. (They’re also a great way to add sentence variety to your writing.)
3 Examples of Compound-Complex Sentences
To help you get a better idea of what this type of sentence looks like in action, we’ve pulled together three compound-complex sentence examples and broken them down so you can see the different parts of compound-complex sentences and how they work together.
Example #1: Ending With Two Independent Clauses
Though Jada was afraid, she gathered her courage and she opened the door.
We know that compound-complex sentences contain at least three clauses, so let’s break down the clauses in that sentence:
Independent clause: she gathered her courage,
Independent clause: and she opened the door.
The sentence above qualifies as a compound-complex sentence because it’s composed of at least one dependent clause and two independent clauses.
Example #2: Starting With Two Independent Clauses
Khalid got on the road early, but he arrived late because he hit rush hour traffic.
This example of a compound-complex sentence has three clauses, but in contrast to the first example, it begins with two independent clauses that are separated by a coordinating conjunction, “but.” Instead of beginning with a dependent clause, this sentence ends with a dependent clause that is introduced with the subordinating conjunction “because.” Here’s a breakdown of the clauses in the sentence above:
Independent clause: Khalid got on the road early,
Independent clause: but he arrived late
Dependent clause: because he hit rush hour traffic.
Now, remember, most of the time, you don’t need a comma to separate independent clauses and dependent clauses if the dependent clause comes after the independent clause, like in the example above.
Example #3: Two Independent Clauses and Two Dependent Clauses
After everyone went home, though the kitchen was a mess, I left the dirty dishes out and I went to bed.
This example includes two independent clauses--like the first two examples--but differs from the first two examples because it includes two dependent clauses.
It’s pretty easy to pick out where the clauses are split up in the example above because of the commas, but let’s go ahead and break it down:
Dependent Clause: After everyone went home,
Dependent Clause: though the kitchen was a mess,
Independent Clause: I left the dirty dishes out,
Independent Clause: and I went to bed.
In this case, you can find the dependent clauses by looking for subordinating conjunctions (“after” and “though”). The independent clauses are easier to find, especially since they’re joined by “and”...which you now know is a coordinating conjunction!
As you can see, compound-complex sentences can start getting pretty long depending on how many clauses you include! But that’s actually one of the perks of compound-complex sentences: they allow you to effectively communicate an extended idea or part of a story or argument. This means that compound-complex sentences can play an important role in sentence variety in your writing, just like complex sentences and compound sentences.
6 Question Quiz: Practice Your New Sentence Knowledge!
We’ve covered a lot of info about complex, compound, and compound-complex sentences, so it might be helpful to review what you’ve learned.
Take a crack at answering the following six questions about the types of sentences we’ve covered, and see if you can pick out the correct examples of each type of sentence as well!
1) What’s the difference between an independent clause and a dependent clause?
a) An independent clause has a subject and a verb, but a dependent clause doesn’t.
b) An independent clause can stand-alone as a sentence, but a dependent clause can’t.
c) An independent clause always includes an adjective, but a dependent clause doesn’t.
2) What is a complex sentence?
a) A complex sentence is made up of two independent clauses.
b) A complex sentence is made up of two dependent clauses.
c) A complex sentence is made up of one independent clause and at least one dependent clause.
3) What’s the definition of a compound-complex sentence?
a) A compound-complex sentence is made up of at least two dependent clauses and at least one independent clause.
b) A compound-complex sentence is made up of at least two independent clauses and at least one dependent clause.
c) A compound-complex sentence is made up of two independent clauses and two dependent clauses.
4) Which of the following is an example of a complex sentence?
a) I went for a quick walk while the sun was out.
b) I waited on the sun to come out, and I went for a quick walk.
c) Though it had been drizzling all morning, I waited for the sun to come out, and I went for a quick walk.
5) Which of the following is an example of a compound sentence?
a) We played hard, and we won the game.
b) We won the game because we played hard.
c) We won the game, we played hard.
6) Which of the following is an example of a compound-complex sentence?
a) After we went swimming, though we were tired, we went to the movies.
b) Though we were tired, we went to the movies, and we had a great time.
c) After we went swimming, we weren’t tired, we went to the movies.
So, how did you do? If you got B, C, B, A, A, and B, you totally aced it!
If you didn’t, that’s okay: luckily for you, it’s easy to practice identifying complex sentences. All you have to do is look at real-life writing examples like books, academic articles, or sample papers. They’ll contain a variety of sentence types, so you’ll have plenty of practice picking out complex sentences.
When it comes to sentences, there’s a lot to learn. This post will help you find sentence fragments and run-ons in your writing, and this post will give you general strategies for identifying sentence errors.
Knowing your way around sentence structure is key to writing killer admissions essays. Did you know that we have comprehensive guides for tackling admissions essays for the nation’s top colleges? We have comprehensive guides to admissions essays for Harvard, Notre Dame, USC, Yale, and more!
But before you tackle admissions essays, you’ll have to knock your SAT and ACT essays out of the park. Check out our comprehensive guides to acing your SAT essays and your ACT essays to set yourself up for success.
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Ashley Sufflé Robinson has a Ph.D. in 19th Century English Literature. As a content writer for PrepScholar, Ashley is passionate about giving college-bound students the in-depth information they need to get into the school of their dreams.