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University of Illinois at Urbana-Champaign

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Writers Workshop: Writer Resources

Grammar Handbook: Restrictive and Nonrestrictive Clauses

A modifying clause can be either restrictive or nonrestrictive.

Restrictive Clause

A restrictive modifying clause (or essential clause) is an adjective clause that is essential to the meaning of a sentence because it limits the thing it refers to. The meaning of the sentence would change if the clause were deleted. Because restrictive clauses are essential, they are not set off by commas.

Nonrestrictive Clauses

A nonrestrictive modifying clause (or nonessential clause) is an adjective clause that adds extra or nonessential information to a sentence. The meaning of the sentence would not change if the clause were to be omitted. Nonrestrictive modifying clauses are usually set off by commas.