Conjunctions

Learning Objectives

  • Correctly identify and use conjunctions in a sentence

Conjunctions are the words that join together sentences, phrases, and other words. Conjunctions are divided into several categories, each of which follows different rules.

Watch It

This SchoolHouse rock video on conjunctions has withstood the test of time—made in 1973, it remains relevant and entertaining today. Watch it for an overview of what conjunctions are and what they do.

You can view the transcript for “Schoolhouse Rock: Grammar- Conjunction Junction Music Video” here (opens in new window).

Coordinating Conjunctions

A compass.The most common conjunctions are andor, and but. These are all coordinating conjunctions. Coordinating conjunctions are conjunctions that join -or coordinate- two or more equivalent items (such as words, phrases, or sentences).

The acronym FANBOYS can be used to remember the most common coordinating conjunctions: for, and, nor, but, oryet, and so.

Examples: Coordinating Conjunctions

Here are some examples of coordinating conjunctions used in sentences:

  • Nuclear-powered artificial hearts proved to be complicated, bulky, and expensive. (Here, the conjunction connects three items in a list, so we need commas.)
  • Any external injury or internal injury puts patients at risk of uncontrolled bleeding. (Here, the conjunction connects two equivalent items but not independent clauses, so we do not use a comma.)
  • The current from the storage batteries can power lights, but the current for appliances must be modified within an inverter. (Here, the conjunction connects two equivalent items -independent clauses that could stand on their own – so a comma is needed).

As you can see from the examples above, a comma only appears before these conjunctions sometimes. So how can you tell if you need a comma or not? There are three general rules to help you decide.

Rule 1: Joining Two Complete Ideas

Let’s look back at one of our example sentences:

The current from the storage batteries can power lights, but the current for appliances must be modified within an inverter.

There are two complete ideas in this sentence (a complete idea has both a subject and a verb). Because each of these ideas could stand alone as a sentence, the coordinating conjunction that joins them must be preceded by a comma. Otherwise you have a run-on sentence.

Run-on sentences are one of the most common errors in college-level writing. Here’s some key information to remember:

Correct: One standalone sentence is fine, but two standalone sentences can be joined with a comma and coordinating conjunction.

Incorrect (comma splice): One standalone sentence is fine, two standalone sentences with just a comma and no coordinating conjunction is a comma splice. (The coordinating conjunction is missing here.)

Incorrect (run-on): One standalone sentence is fine two standalone sentences together with no comma and no coordinating conjunction are a run on. (We need the coordinating conjunction and the comma here!)

Rule 2: Joining Two Similar Items

What if there is only one complete idea but two subjects or two verbs? Consider the following examples:

  1. Any external injury or internal injury puts patients at risk of uncontrolled bleeding.
  2. In the 1960s, artificial heart devices did not fit well and tended to obstruct the flow of venous blood into the right atrium.

The first sentence has two subjects: external injury and internal injury. They are joined with the conjunction or. The second sentence has two verbs: did not fit well and tended to obstruct. They are joined with the conjunction and. We DO NOT use a comma with a coordinating conjunction when we are joining two subjects or two verbs, only when we are joining two complete ideas (or sentences that could stand on their own).

Rule 3: Joining Three or More Similar Items

What do you do if there are three or more items?

Examples: Joining 3+ items

  • Anna loves to run, David loves to hike, and Luz loves to dance.
  • Fishing, hunting, and gathering were once the only ways for people to get food.
  • Emanuel has a very careful schedule planned for tomorrow. He needs to work, study, exercise, eat, and clean.

As you can see in the examples above, there is a comma after each item, including the item just before the conjunction (and). There is a bit of contention about that final comma, but most styles prefer to include it (it’s called the serial comma).

Two thought bubbles.Adverbial Conjunctions

Adverbial conjunctions, or conjunctive adverbs, link two separate thoughts or sentences. When used to interrupt thoughts, a comma is required on either side of the conjunction.

  • The first artificial hearts were made of smooth silicone rubber, which apparently caused excessive clotting and, therefore, uncontrolled bleeding.

Examples: interrupting adverbial conjunctions

Incorrect: My sister therefore, is going to be the first transgender supreme court justice.

Correct: My sister, therefore, is going to be the first transgender supreme court justice.

When used to separate complete ideas (independent clauses, which each contain a subject and a verb), a semicolon is required before the conjunction and a comma after.

  • The Kedeco produces 1200 watts in 17 mph winds using a 16-foot rotor; on the other hand, the Dunlite produces 2000 watts in 25 mph winds.
  • This is a complete sentence; however, this is also a complete sentence.

Examples

Incorrect: Mexican-Americans are described by a variety of names in the United States, for example, Latine, Chicano, and Hispanic are all terms used to describe Americans of Mexican descent. (connecting)

Correct: Mexican-Americans are described by a variety of names in the United States; for example, Latinx, Chicano, and Hispanic are all terms used to describe Americans of Mexican descent.

Be careful to think about whether the adverbial conjunction is interrupting (like therefore above) or connecting (like on the other hand or for example).

Adverbial conjunctions include the following words; however, it is important to note that this is by no means a complete list.A balanced scale.

therefore however in other words
thus then otherwise
nevertheless on the other hand in fact

Correlative Conjunctions

Correlative conjunctions are word pairs that work together to join words and groups of words of equal weight in a sentence.

The table below shows some examples of correlative conjunctions used in sentences:

Correlative Conjunction Example
either . . . or You either do your work or prepare for a trip to the office. (Either do, or prepare)
neither . . . nor Neither the basketball team nor the football team is doing well.
not only . . . but (also) He is not only handsome but also brilliant. (Not only A but also B)
Not only is he handsome, but also he is brilliant. (Not only is he A, but also he is B)
both . . . and Both the cross-country team and the swimming team are doing well.

Be careful! Correlative conjunctions can give you subject and verb agreement issues.

Correct: Neither the teacher nor the students are happy.

Incorrect: Neither the teachers nor the student are happy.

The verb m matches the closest the subject. We reviewed this in the Verbs section.

Subordinating Conjunctions

Subordinating conjunctions are conjunctions that join an independent clause and a dependent clause. The most common subordinating conjunctions in the English language are shown in the table below:

after although as as far as as if as long as as soon as
as though because before even if even though every time if
in order that since so so that than though unless
until when whenever where whereas wherever  while

Examples: Subordinating conjunctions

Here are some examples of subordinating conjunctions:

  • The heart undergoes two cardiac cycle periods: diastole, when blood enters the ventricles, and systole, when the ventricles contract and blood is pumped out of the heart.
  • Whenever an electron acquires enough energy to leave its orbit, the atom is positively charged.
  • She did the favor so that he would owe her one.

Let’s take a step back and look for a pattern in comma usage. Commas aren’t based on whether a subordinating conjunction is present—they depend on the placement of the clauses.

Some clauses add extra information that isn’t necessary for the main meaning of the sentence. These nonessential clauses need commas to separate them from the rest of the sentence.

Example: Nonessential clauses

Example: The heart undergoes two cardiac cycle periods: diastole, when blood enters the ventricles, and systole, when the ventricles contract and blood is pumped out of the heart.

Without extra information: The heart undergoes two cardiac cycle periods: diastole and systole.

In the first sentence, the extra details about when blood enters and exits the heart are helpful but not essential. That’s why they’re set off with commas.

A dependent clause cannot stand alone as a full sentence, while an independent clause can.

Examples: Dependent and independent clauses

Example: Whenever an electron acquires enough energy to leave its orbit, the atom is positively charged.

As seen in the example above, when a dependent clause comes before an independent clause, it should be followed by a comma.

  • A complete sentence (Independent clause): The atom is positively charged.
  • Not a complete sentence (Dependent clause): Whenever an electron acquires enough energy to leave its orbit.

If a dependent clause follows an independent clause, no comma is needed.

  • Example (No Comma Needed): She did the favor so that he would owe her one.

But if the dependent clause comes first, you do use a comma:

  • Example (Comma Needed): So that he would owe her one, she did the favor.

Key Takeaway: Comma usage and placement

Dependent clause first → Use a comma

  • Whenever an electron acquires enough energy to leave its orbit, the atom is positively charged.

Dependent clause after → No comma

  • She did the favor so that he would owe her one.

Extra (nonessential) information → Use commas on both sides

  • The heart undergoes two cardiac cycle periods: diastole, when blood enters the ventricles, and systole, when the ventricles contract and blood is pumped out of the heart.

Watch IT

If you feel like you need some additional help understanding the difference between independent and dependent clauses (which is key to using subordinating conjunctions), check out this video.

You can view the transcript for “Subordinating Conjunctions” here (opens in new window).

Try It