Adjective Clauses, Part 2 (Commas)

We know that an adjective clause is a group of words that begins with a relative pronoun, has its own subject, verb, and idea, and is used to give us more information about a noun in a sentence. (See Adjective Clauses: Part 1 for more information).

Click here for a review of adjective clauses

Let's look at these two examples:

• People who can’t swim should not jump off the boat. (*notice there are no commas)
• My Uncle John, who couldn’t swim, did not jump off the boat. (*commas!)

But what about these commas? How do we know when we need them?

Adjective clauses can fall into these two categories:

1. Identifying (*no commas)

• (These are also sometimes called “ESSENTIAL,” “RESTRICTIVE,” or “DEFINING” adjective clauses)
• They give us information that IDENTIFIES a noun in the sentence
• They are NECESSARY to understand who or what we are talking about
• Will often start with “that” instead of “which”
• No commas needed
• EXAMPLE: People who can’t swim should not jump off the boat. (We need the adjective clause to identify which people we are talking about. Who should not jump off the boat?)

2. Non-Identifying (*commas needed)

(These are also sometimes called “NON-ESSENTIAL,”  “NON-RESTRICTIVE,” or “NON-DEFINING” adjective clauses)

Give us extra information about a noun in the sentence, describes a noun in the sentence

BUT they are not necessary to understand who or what we are talking about

Cannot start with “that” (“which” is used for objects)

Comma before, comma after (to separate it from the main clause)

EXAMPLE: My Uncle John, who couldn’t swim, did not jump off the boat. (The adjective clause is helpful and gives us important information, BUT we do not need it to identify my Uncle John.)

Here is a little YouTube video of a teacher explaining restrictive and non-restrictive clauses with some good, clear examples. CLICK HERE.

For practice, try these exercises:

Practice 1 (an explanation, followed by an exercise. You must decided if each clauses is IDENTIFYING or NON-IDENTIFYING)
Practice 2 (this must be printed. The first exercise is related to commas- the second is not!)
Practice 3 (a good one!)