Relative Clauses

Relative Clauses

Sometimes, you may need or want to add additional information to a noun in a sentence for clarity, context, or style. One way to do this is to add an adjective (for example, “red ball”). Functioning similarly to an adjective, a relative clause (also known as an adjective clause) is a type of dependent clause that describes a noun. However, unlike an adjective, a relative clause follows the noun it’s describing and, like other clauses, always contains a subject and a verb.  Grammar and style guides sometimes disagree on how to form relative clauses. This chapter presents rules to form relative clauses that sound grammatical to native English speakers. Most importantly, relative clauses are useful to combine simple sentences into a complex sentence. For example:

  1. Amanda is a senior nun.
  2. Amanda works at an old Christian church.
  3. Amanda, who works at an old Christian church, is a senior nun.

The “Amanda” in the second sentence was replaced with the pronoun who in the third sentence, and the newly formed relative clause “who works at an old Christian church” was embedded into the first sentence to create a new, complex sentence. When forming sentences with relative clauses, which pronoun to use partly depends on if the pronoun functions as the subject or object in the relative clause. It also depends on whether the noun is alive; who and that can refer to people and animals, that can also refer to things, and which can only refer to things. In sentence 3 above, the word “Amanda” becomes the subject relative pronoun “who” when it gets embedded as a relative clause. See the flowcharts at the end of the chapter for more examples.

Click each drop-down arrow to learn more about Relative Clauses

Clause Types

Two main types of relative clauses exist:

  • restrictive relative clause (also known as an essential or limiting clause) contains information necessary to identify (or restrict) the noun it’s describing and is not separated out with commas. You can use the pronouns whothatwhom, and whose to refer to people, animals and things. Please note that style and grammar guides disagree on whether which can be used in restrictive relative clauses, but that is often preferred.
  • non-restrictive relative clause (also known as a non-essential or non-limiting clause) contains information that is not necessary to identify (or restrict) the noun it’s describing and is separated out with commas to indicate that the clause is grammatically unnecessary. While restrictive relative clauses can only describe nouns, non-restrictive relative clauses can also describe the entire clause it’s attached to. You can use the pronouns whowhichwhom, and whose to refer to people, animals or things. Please note that that can never be used in non-restrictive relative clauses.
Deciding Which Type of Clause to Use

Determining whether a noun needs further explanation often depends on the context and assumed knowledge of the audience. If you are unsure, you can use the following test to determine if the relative clause is restrictive (necessary) or not:

  • If the question “which [noun]?” is logical because you need additional information to answer it, then use a restrictive relative clause:
    1. Police should only doubt the [people].
    2. Which [people]?
    3. Police should only doubt the [people] who act suspiciously. (The relative clause “who act suspiciously” is required to restrict the meaning of the preceding noun, “people”; otherwise, the readers do not know who the police should doubt. This assumes you have not previously given appropriate context about the people whom police doubt.)
  • If the question “which [noun]?” is illogical because you do not need additional information to understand the noun, then use a non-restrictive relative clause:
    1. [Amanda] had a mom.
    2. Which [Amanda]? (This question is illogical, assuming you previously have defined who Amanda is.)
    3. [Amanda], who is a little girl with long hair, had a mom. (Here, “Amanda” is a unique noun that does not need additional information to define it.)

Here is a visual way to see the difference between restrictive and non-restrictive relative clauses.  The following sentence can be interpreted as a restrictive or non-restrictive relative clause, depending on the context:

Example 1: Half the B Street apartments which are owned by landlords are already rented.

Relative Clause Example 1a
  • The restrictive relative clause “which are owned by landlords” restricts the noun phrase that precedes it (“half the B Street apartments”). Without commas, the restrictive relative clause adds additional necessary information to limit the subgroup of “half the B Street apartments” to only those which are owned by landlords. 

Relative Clause Example 1b

Example 2: Half the B Street apartments, which are owned by landlords, are already rented.

Relative Clause Example 2

  • The non-restrictive relative clause “which are owned by landlords” applies to the entire noun phrase that precedes it (“half the B Street apartments”). By using commas, the non-restrictive relative clause adds additional information to “half the B Street apartments” without limiting its subgroup to only those which are owned by landlords.
Reducing Relative Clauses
  • Restrictive Clauses: To make your writing more concise, you can reduce most types of restrictive relative clauses. For non-subject clauses, simply delete the pronoun. For subject clauses, delete the pronoun and the to be helping verb if you have one and change the main verb to the –ing form with active meaning or –ed form with passive meaning (for example, “Police should only doubt the people who act suspiciously” can be reduced to “Police should only doubt people acting suspiciously.”). However, indirect object clauses can only be reduced when the preposition is at the end of the clause, and possessive clauses can never be reduced.
  • Non-Restrictive Clauses: Many sources disagree about whether non-restrictive relative clauses can be reduced, and some sources call this reduced form an appositive (a noun that defines another noun). In general, you want to make sure your writing is clear and grammatical to the reader, so you should choose a style that best helps you make your point. In most cases, only subject and direct object relative clauses using a to be verb can be reduced by deleting the pronoun and to be verb (for example, “Amanda, who is a girl with long hair, had a mom” can be reduced to “Amanda, a girl with long hair, had a mom.”).

Restrictive Relative Clause Flowchart and Examples

The flowchart shows which relative pronoun to use (who, whom, whose, that, which), whether it’s possible to reduce the form, and an example sentence of each clause type. Please click here to download a PDF version of this flowchart.

restrictiveclause

Non-restrictive Relative Clause Flowchart and Examples

The flowchart shows which relative pronoun to use (who, whom, whose, that, which), whether it’s possible to reduce the form, and an example sentence of each clause type. Please click here to download a PDF version of this flowchart.

Nonrestrictivechart