Writing Center Handouts

That and Which in Restrictive and Non-restrictive Clauses

A restrictive clause is one that contains information essential to the meaning of the sentence; therefore, no commas are used around it.

The identified agency that was responsible for the boy's future was ACS.

The clause "that was responsible for the boy's future" is essential to the meaning of the sentence. It restricts the agency that the writer refers to.

A non-restrictive clause is one that contains information not essential to the meaning of the sentence; therefore, commas are used around it.

ACS, which was the identified agency, was responsible for the boy's future.

The clause "which was the identified agency" is not essential to the meaning of the sentence. It provides additional information of some kind.

When using the words that or which to introduce a clause, first ask yourself whether the statement you're writing is essential to the meaning of your sentence. If it is, then begin it with the word that (without a comma before it). If it is not essential, then use the word which with a comma before it.

For class the students needed pencils that were durable.

For class the students needed durable pencils, which were expensive.

I can't miss the lecture that will be on current social policy initiatives.

The subject of the lecture, which is one I can't miss, will be current social policy initiatives.

The New York that I know and love is beginning to change.

New York, which is beginning to change, is the city I know and love.

The class that met from 9 to 11 on Wednesday was full.

The class, which met from 9 to 11 on Wednesday, was full.

And keep in mind that the above applies to more than clauses introduced by either that or which. Use commas around any statement that describes or provides additional information about the main clause.

The class, no matter what anyone said, was stimulating.

My HBSE professor, who's my current favorite in the whole world, was voted outstanding teacher.

The professor, when she thought appropriate, challenged the students to perform at a higher level.

The atrium, where the luncheon was to be held, had already been booked.

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