Grammarama

Relative Clauses

Relative clauses are a special type of dependent clause. For more information on clauses, see "Clauses" . Relative clauses supply more information about a noun without creating a whole new sentence to convey that information. They begin with relative pronouns like who, which, whose, whom, and that or the relative adverbs when, where, and why.

The most important thing we need to figure out when it comes to a relative clause is whether it’s essential or non-essential (synonymous with restricting/non-restricting and defining/non-defining). This is because non-essential clauses should be set off by commas, whereas essential clauses are essential to understanding the rest of the sentence and therefore should not be surrounded by commas. A relative clause’s antecedent—that is, the noun it modifies—should immediately precede it in either case.

Would it be clear who or what is being spoken of without the relative clause in the sentence? If so, it’s non-essential. Take the following sentence without a relative clause:

My mother has been to every continent except Antarctica.

In the purest sense of the word, none of us have more than one mother, so any relative clause applying to “mother” would be non-essential:

My mother, who is 70 years old, has been to every continent except Antarctica.
My mother, who is retired, has been to every continent except Antarctica.
My mother, whom I visit every week, has been to every continent except Antarctica.

When adoption and/or remarriage come into play, we can have an adoptive mother and/or step-mother(s) in addition to a biological mother, but they should be differentiated using those terms, not relative clauses. When we say only “mother,” it should be clear whom we mean by that, biological mother or not.

How about a brother? Since we can have more than one brother, the essentialness of a relative clause depends on the circumstances. If someone only has one brother or the brother in question is clear through the context, then it’s non-essential just like for mother:

My brother, who is my only sibling, is a Rhodes Scholar.

On the other hand, if someone has more than one brother, and the brother in question is not clear through context, then the relative clause is essential:

My brother who lives in Texas is coming for Thanksgiving, but my brother who lives in Florida isn’t.

If you take those relative clauses out of the sentence, it’s painfully obvious just how essential they are:

My brother is coming for Thanksgiving, but my brother isn’t.

Make up your mind already!


Examples:

Who is used in both essential and non-essential relative clauses when the antecedent is a person:

Are you the one who keeps calling me?
I only told Jenny, who is my best friend.

When the antecedent is not a person, that is usually used for essential clauses; however, which can also be used, especially when another “that” appears nearby. That, on the other hand, can not be used as the relative pronoun for non-essential clauses; you must use which.

The chair that came from the neighbor’s garage sale is very comfortable.
We bought a new refrigerator, which has a built-in ice dispenser.

This is the house where I grew up.
We took a family vacation to Utah, where we visited many national parks.
There was a time when dinosaurs roamed the Earth.
I was born in 1944, when the United States was fighting in World War II.