Grammar: Adjective Clauses and How to Punctuate Them

Adjective Clause Words

An Adjective Clause is a group of words that acts like an adjective to modify a noun or noun phrase. They are often introduced with the pronouns who, which, that, whom, and whose; the adverbs where, when, and why; or nothing, called a zero relative, where one of the above words is only implied.

Adjective Clauses Introduced with Pronouns

My friend told me she had a crush on the man who was wearing a green hat.

Jeremy, who badly needed a good night of sleep, stumbled to the library for an all-night cram session.

My wife, whom I’ve been married to for 30 years, still surprises me.

The flowers, which Lucy picked this morning, are already wilting.

The mice that live in the attic keep me awake at night.

The bikers, whose shoulders gleamed with sweat, rode past the cheering crowd.


Practice: Read the following sentences and pick out the adjective clauses:

A person who can’t admire a sunset will never be very happy.

My best friend, who grew up in Tucson, still loves the desert more than anywhere else.

The children, who were in the country for the weekend, went to pick the water lilies that grew on the top of the pond.

The teacher didn’t like to call on Robert, whose answers were often very philosophical and strange, even though he always raised his hand.

Answers here.

Adjective Clauses with Adverbs:

Adverbs often introduce adverbial clauses, modifying verbs, but in many cases they also modify nouns regarding place, time and reason.

The children waited for Christmas morning, when they would open their presents under the tree.

I wouldn’t tell anyone the reason why my mom didn’t pick me up after school.

The house where I grew up is painted pink now.


Practice: Read the following sentences and pick out the adjective clauses:

I look forward to the day when I can say “I’ve been a podiatrist for 20 years!”

Even though he was upset, Mark understood the reasons why his wife had left him.

I want to travel to a place where my cellphone doesn’t work.

Answers here.

Zero Relatives:

Sometimes you can omit the pronoun or adverb introducing a relative clause without changing the meaning of the sentence. It is very common to drop the “that” pronoun. In these cases, you say that the clause has a zero relative, noted here by the symbol Ø .

The woman Ø (whom) the boss finally hired turned out to be his sister’s friend.

That’s the dress Ø (that) I’ve been looking at.

I don’t agree with anything Ø (that) you are saying.

I think the poem Ø (that) you wrote was really good.


Practice: Read the following sentences and pick out the zero-relative adjective clauses:

I think the books you like are all really good.

The man I ran into at the store called me the next day.

The teacher I had in grade school is still teaching there.

Answers here.

But what about commas?!?

Have you noticed that in all the above examples, some adjective clauses are set off by commas, and some aren’t? Why!?! The answer is that there are two main types of adjective clauses: Nonrestrictive (or nonessential) and Restrictive (or essential) adjective clauses.

Nonrestrictive Clauses give extra information about the noun they’re modifying. They are called nonessential because they don’t change the ultimate meaning of a sentence. These kinds of clauses are set apart by commas. Consider the sentence: My history professor, who loves eating ice cream, took us to the ice-cream parlour on the last day of class. “Who loves eating ice cream” is non-essential, extra information and is set off by commas.

Restrictive Clauses give information that is essential to the meaning of the sentence, and make the noun more specific. Restrictive clauses are not set apart by commas. Consider the sentence, Children who ride their bikes without a helmet are at risk for injury. The sentence isn’t talking about all children, only those “who ride their bikes without helmets.” This adjective clause narrows down (restricts) the noun, and is essential to understand the meaning of the sentence.


The pronouns which and that are used for nonrestrictive and restrictive clauses, relatively. Clauses beginning with the word “thatare never set apart by commas. Consider these two sentences:

The branches, which had been knocked down in the storm, lay in the back yard.

The branches that had been knocked down in the storm lay in the back yard.

They use almost all the same words, but the meanings are slightly different. In the first sentence, the “which had been knocked down by the storm” clause gives extra information about the branches. Everyone already knows which branches you are talking about. In the second sentence, “that had been knocked down in the storm” specifies or restricts the noun it modifies, the branches. Whoever you are talking to doesn’t know which branches you are talking about; you need to tell them you are talking about only the branches that had been knocked down by the storm.


These are examples of nonrestrictive adjective clauses, with commas:

The baseball player, whose batting average had been .431 all season, struck out.

I spent the whole afternoon looking at the cherry trees, which had acquired new spring flowers seemingly overnight.

The dog started waiting by the door at 4:45 every day, and sat there patiently until 5:00, when his owner came home.


These are examples of restrictive adjective clauses, without commas:

Birds who fly south for the winter can tell direction based on the earth’s magnetic field.

The mushrooms that come up every spring in the woods by my house look delicious.

I gave some money to a man who asked for it.

Let’s go to a restaurant where we can get bubble tea.


Practice: Read the following sentences, which may or may not be correctly punctuated. Decide if you should add commas based on whether or not the adjective clause is restrictive or nonrestrictive.

The Great Barrier Reef which is slowly disappearing is home to many kinds of fish and sea animals.

The dog that bit me went to dog-therapy and is better now.

I hope I don’t become one of those people who owns 20 cats in middle age.

Lucy who wore a purple sweater and Jane who wore green tights and an orange dress stuck out in the crowd of brown-coated businessmen.

I don’t understand people who don’t like comedy.

The library books which were red and green looked like a Christmas decoration.

Answers here.


More Practice: Make these short sentences more interesting by inserting an adjective clause. Remember to set it off with commas if necessary!

The hat fell to the ground.

Louise caught the cat.

Farmers grow food.

I biked all the way across town.

I’ll see you on Monday.

The owl was visible in the moonlight.

Jeremy and Chris walked on a tightrope.