Relative Clauses

Form

A relative clause adds information about a noun, and it opens with a relative pronoun that stands in for that noun.

Use who for people, which for things, that for either, whose for possession, where for places, when for times, and why after the word reason (the man who called, the book which arrived, the city where I grew up). A defining clause says which one you mean and takes no commas (The report that I sent was wrong); a non-defining clause adds an extra detail about something already identified, sits between commas, and can never use that (My boss, who is new, approved it). In a defining clause only, you can leave the pronoun out when it is the object of that clause (the book I read) — never when it is the subject (the book that arrived), and never after a preposition, where formal writing uses whom or which (the colleague with whom I trained).

When to Use It

1. 1

   Use who for a person and which for a thing, with that available for either in a defining clause

   The engineer who designed it still works here.

2. 2

   Use whose to show that the noun after it belongs to the person or thing

   The scientist whose research led to the vaccine won an award.

3. 3

   Leave the commas out when the clause identifies which one you mean, because the sentence needs it

   The email that arrived this morning was urgent.

4. 4

   Put commas around the clause when it only adds extra detail, and use who or which rather than that

   My manager, who started in March, approved the budget.

5. 5

   Use where or when instead of a preposition plus which for places and times

   That is the cafe where we first met.

6. 6

   Drop the pronoun in a defining clause when it is the object of that clause, in writing as much as in speech

   The movie I watched last night was excellent.

Common Mistakes

• That after a comma: write My father, who is a doctor, works nights, not My father, that is a doctor, works nights — a non-defining clause takes who or which.
• Who for a thing: write a company which was founded in 1985, not a company who was founded in 1985 — who is only for people.
• Doubling the noun: write the house that I bought, not the house that I bought it — the relative pronoun already stands in for the noun, so no extra it follows.
• Dropping a subject pronoun: write The train that arrives at six is fast, not The train arrives at six is fast — you can leave the pronoun out only when it is the object.
• What for that: write everything that she needs, not everything what she needs — what is never a relative pronoun after a noun.