relative pronouns, who, whom, whose, which, that

Pronouns are words that take the place of a noun. Relative pronouns are used at the beginning of an adjective clause (a dependent clause that modifies a noun). The three most common relative pronouns are who, which and that.

Who has two other forms, the object form whom and the possessive form whose.

• Who and whom are used mainly for people. However, these pronouns can also be used to refer to animals that are mentioned by name and seen as persons.
  • The musician who wrote this song is Canadian.
  • The witnesses whom I interviewed gave conflicting evidence.
  • The vacuum scared our cat Scooter, who was sleeping on the rug.
• Whose can be used for people, animals or things:
  • The man whose daughter won the tournament is a tennis coach.
  • A dog whose owner lets it run loose may cause an accident.
  • The tree whose branches shade my kitchen window is an oak.

Which is used for animals in general or things.

• Bridget visited the park with her dog, which likes to chase squirrels.
• Jason bought the top hybrid car, which will help him save on gas.

That can be used for people, animals or things.

• The musician that won the award is Canadian.
• The car that Jason bought runs on electricity and gas.
• The dog that is chasing the squirrels belongs to Bridget.

That vs. which

That and which are used to start two different types of adjective clauses, called essential and non-essential clauses.

Essential clauses

That always indicates a clause that is essential to the meaning of the sentence because it defines or identifies the noun it refers to. An essential clause does not take a comma before it.

• Lisa wore the shoes that she bought in Italy.
  (What shoes? The ones that she bought in Italy. The clause identifies the shoes.)

Which may also be used to introduce an essential clause.

• Lisa wore the shoes which she bought in Italy.

Non-essential clauses

Which is used in a non-essential clause modifying an animal or a thing. A non-essential clause is one that gives secondary, non-essential information about a noun that is already fully identified. A non-essential clause is separated from its noun with a comma:

• Lisa wore her best leather shoes, which she bought in Italy.
  (What shoes? Her best leather ones. The clause is not needed to identify the shoes, so it is non-essential.)

Who vs. whom

The relative pronoun who may cause confusion because it has both a subject form (who) and an object form (whom). The key to choosing between these forms is to see what the pronoun is doing in its own clause.

Use who if the pronoun is the subject of the verb in the dependent clause.

• The people who just boarded the plane are in a rock band.
  (The pronoun is subject of the verb boarded.)

Use whom if the pronoun is the object of the verb in the dependent clause.

• The cousin whom we met at the family reunion is coming to visit.
  (The pronoun is object of the verb met.)

Use whom if the pronoun is the object of a preposition in the dependent clause.

• The agent with whom I spoke was able to help me.
  (The pronoun is object of the preposition with.)

Tips

If in doubt, reword the clause to see which personal pronoun you need: he/him, she/her, etc. Then replace that pronoun with who or whom, using the following rule:

• Use WHO for he, she, they, we:
  • The people who just boarded the plane are in a rock band.
    (Reword: They just boarded the plane—so use who.)
• Use WHOM for him, her, them, us:
  • The cousin whom we met at the family reunion is coming to visit.
    (Reword: We met him at the family reunion—so use whom.)
  • The agent with whom I spoke was able to help me.
    (Reword: I spoke with her—so use whom.)