Restrictive and Non-Restrictive Adjective Clauses
A restrictive adjective clause limits or narrows the meaning of the sentence in which it appears.
The sentence must have that clause or the meaning changes; in other words, the clause is
necessary to the meaning. Because they are essential to the sentence, restrictive adjective clauses
can never be set off from the sentence with punctuation.
Examples:
High-risk students who attended extra tutoring sessions had significantly higher grades than students who
did not attend.
(The clause in italics is necessary to the sentence. If we took it out, the meaning of the sentence
would change drastically; therefore, there should be no punctuation to set off the restrictive
element here.) Look at the difference when the sentence is written incorrectly.
High-risk students, who attended extra tutoring sessions, had significantly higher grades than students who
did not attend.
Correct: Students who have not signed in at the desk will not receive assistance.
Incorrect: Students, who have not signed in at the desk, will not receive assistance.
Correct: Students who have done or attempted to do their homework can check their answers against the
professor’s answer sheet.
Incorrect: Students, who have done or attempted to do their homework, can check their answers against the
professor’s answer sheet.
A clause is non-restrictive if it is not strictly necessary to the meaning of the sentence. It can be
left out and the sentence will still be logical. The non-restrictive clause merely gives the reader
extra information. Imagine that you could lift the non-restrictive clause out of the sentence,
using the commas as handles, and the sentence could still function. That is why the clause is
called “non-restrictive”: it does not restrict the sentence, or the sentence is not restricted to
containing the clause.
Examples:
Non-traditional students, who are generally highly motivated, tend to do well on the sample tests.
The cat, who had already spent eight of his nine lives, was spared from tragedy once again.
In both examples containing non-restrictive clauses, the material between commas could be
“lifted” out without changing the general meaning of the sentences. That material gives extra but
not essential information. In sentences containing restrictive clauses, the material cannot be
“lifted” out and should not be enclosed by commas.
