Who, That, Which

It can sometimes be confusing when to use who, that, or which. Following are some helpful guidelines.

Relative Pronouns

Who, that, and which are relative pronouns. A relative pronoun comes after a noun to a) identify or describe the particular person or thing being talked about or b) provide more information about a person or thing. That information is usually in the form of a Relative Clause or adjective clause, and contains several words, including a subject and a verb. Relative clauses are two types: Restrictive Clauses (as in (a), above) and Nonrestrictive Clauses (as in (b) above).

Restrictive and Non-Restrictive Clauses

Restrictive Clauses limit or restrict the possible identity or meaning of a preceding subject. Since they provide important or essential information to narrow down possibilities, they’re often called Essential Clauses. These clauses cannot be removed from a sentence without changing the sentence’s meaning. Restrictive clauses usually begin with who or that (or whom or whose) and are never set off using commas. Example:

The man who had red hair was tentatively identified as the thief.

The man in this sentence is different from other men who don’t have red hair. This essential piece of information (red hair) makes “who had red hair” a restrictive clause.

Non-Restrictive Clauses tell you something about a preceding subject, but they do not limit or restrict the possible identity or meaning of that subject. Since they provide non-essential, additional, optional, or extra information, they’re often called Non-Essential Clauses. These clauses can easily be removed from a sentence without changing the sentence’s meaning. Non-restrictive clauses usually begin with which or whose and are always set off using commas, indicating that these clauses are removable.

Example: The car, which was painted bright red, was parked illegally in a no-parking zone.

Note that the information about the car’s paint job is superfluous to the fact that it was parked illegally. Since it’s non-essential to the main thought in the sentence, it’s a non-restrictive clause and is set off by commas.

Who, That, or Which?

Who (also whom or whose) is used to refer to people. Sometimes that is used, but most often it’s in informal speech and writing. Many sources suggest not using that for people. So, generally speaking, it’s good form to avoid this usage, especially in formal writing. Examples:

The man who won the contest was celebrated in his home town.

The girl whom everyone likes was voted queen of the parade.

The person whose number was called won the raffle.

That and Which (also whose) is used to refer to things. Use that to introduce a restrictive clause (one that’s essential to the complete meaning of the sentence). Add a comma before which AND add a comma or a period after the non-restrictive clause. Example:

The theater refused to honor tickets that were from a previous day.

Use which to introduce nonrestrictive clauses (one that’s not essential to the complete meaning of the sentence). Add a comma before which AND add a comma or a period after the non-restrictive clause. Example:

The theater refused to honor the tickets, which were from a previous day.

Conclusion

The use of who is relatively straightforward—it applies to people. When to use that and which can be more challenging. Just remember to use that with restrictive clauses and which with nonrestrictive clauses. Here’s a quick tip: If you use which when you can safely throw out the clause and not change the intended meaning of the sentence, you’ll be right most of the time. Consistent use of who, that, and which will help make your writing clearer and more precise.

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