Relative Pronouns (who, which, that, whose, whom)
The connectors that join two clauses around a shared noun. English uses who/whom for people, which for things, that for both. Defining vs. non-defining clauses use different punctuation. Mastering relatives unlocks the long-form sentence flow of English literature.
A relative pronoun connects a noun to a clause that describes or modifies it. The main English relative pronouns are:
- who — people (subject)
- whom — people (object, formal)
- whose — possessive (people or things)
- which — things or animals
- that — people or things (restrictive only)
- where — places
- when — time
- why — reasons
The central skill of English relative clauses is distinguishing defining (restrictive) from non-defining (non-restrictive) clauses. They use different punctuation and slightly different relative pronouns.
Defining vs. non-defining clauses
Defining (restrictive) clauses
These identify which person, thing, or place the speaker means. The clause is essential to the sentence’s meaning. No commas.
The man who lives next door is a doctor. (identifies which man) The book that I bought yesterday is on the table. (identifies which book)
Without the defining clause, the sentence wouldn’t make sense:
- The man is a doctor. (which man?)
- The book is on the table. (which book?)
Non-defining (non-restrictive) clauses
These add extra information about an already-identified noun. The clause is not essential. Set off by commas.
My brother, who lives in Berlin, is a doctor. (we know which brother — there’s only one) Paris, which is the capital of France, is beautiful. (Paris is already known)
You could remove the clause without losing the sentence’s main point.
The crucial test
If you can put the clause in parentheses without losing essential meaning, it’s non-defining (use commas):
My brother (who lives in Berlin) is a doctor. ✅
If removing the clause would create ambiguity, it’s defining (no commas):
The man who lives next door is a doctor. — (The man is a doctor) is vague.
Who, whom, whose — for people
Who — subject of the relative clause
The teacher who taught me French… The man who is talking to Sarah is my uncle.
Whom — object of the relative clause (formal)
The man whom I met yesterday is a doctor. The colleague whom she trusted betrayed her.
In modern English, whom is mostly used in formal writing. Conversational English uses who or that instead:
The man who I met yesterday… (modern, acceptable) The man I met yesterday… (omitted entirely)
Whose — possessive
The author whose book I read is famous. The woman whose car was stolen filed a report.
Whose works for both people and things in modern English:
The car whose wheels are flat is mine. (acceptable, slightly informal)
In formal writing, you might prefer of which for things:
The car, the wheels of which are flat, is mine. (very formal)
Which — for things and animals
Defining
The book which I read was excellent.
In modern English, that often replaces which in defining clauses:
The book that I read was excellent. (more common in spoken English)
Both are correct. Which feels slightly more formal.
Non-defining
Berlin, which is the capital of Germany, has a famous wall.
In non-defining clauses, you must use which, not that:
✅ Berlin, which is the capital, … ❌ Berlin, that is the capital, …
This is one of the strongest rules in English relative pronouns.
That — for people or things (defining only)
That is the most flexible relative pronoun. It can replace who, whom, which in defining clauses (never in non-defining).
The man that I saw… (= who/whom I saw) The book that I read… (= which I read)
But:
❌ Berlin, that is the capital… ✅ Berlin, which is the capital…
In some traditional grammars, who is preferred for people and that for things, but in modern English that is acceptable for both in defining clauses.
Omitting the relative pronoun
When the relative pronoun is the object of the relative clause, English allows you to omit it entirely.
The book (that) I bought is on the table. The man (whom) I saw was tall.
You CANNOT omit the relative pronoun when it’s the subject:
❌ The book is on the table. — needs a complete subject; that I bought needs that if book is the subject of the main clause and the relative clause has its own subject (I).
Actually, the rule: omit only if there’s a different subject in the relative clause. The man (whom) I saw — I is the subject of saw, so whom can be dropped. The man who saw me — who IS the subject of saw, so it must stay.
Where, when, why — for places, times, reasons
These work like relative pronouns for adverbial concepts.
Where — for places
The city where I was born… The house where I grew up…
When — for time
The day when I met her… The year when the war ended…
Why — for reasons
The reason why he left…
In modern English, why is often omitted: The reason he left was unclear.
Prepositions in relative clauses
When the relative pronoun is the object of a preposition, English has two strategies:
Formal: preposition + which/whom
The man with whom I work is friendly. The house in which I live is old.
Casual: pronoun at end of clause
The man (who/that) I work with is friendly. The house (that) I live in is old.
Modern English overwhelmingly prefers the second pattern in conversation. The first sounds bookish or formal.
The friend I went to dinner with… (casual) The friend with whom I went to dinner… (formal)
Reduced relative clauses
In some cases, the relative pronoun + verb can be reduced.
Participle clauses
The man who is sitting there… → The man sitting there… The book which was published in 1900… → The book published in 1900…
The participle (-ing or past) replaces the full relative clause.
Infinitive clauses
The first person who arrived was John. → The first person to arrive was John.
What you don’t need to do
You don’t need to use whom in casual English. Who or omitting the pronoun is acceptable.
You don’t need to use that for everything. Which and who work in defining clauses too.
You don’t need to use full preposition + which form. Trailing prepositions are accepted in modern English.
You don’t need to use why explicitly. The reason he left is fine.
Common confusions
- Defining = no commas, non-defining = commas. This is the foundation rule.
- Use which (not that) in non-defining clauses. Berlin, which is the capital…, never Berlin, that…
- Omit relative pronouns when they’re objects. The book I read (omitting that).
- Don’t omit relative pronouns when they’re subjects. The man who lives next door — who must stay.
- Whose works for things too. The car whose wheels are flat is acceptable.
Where you’ll meet it in the library
Relative pronouns are essential to all complex prose:
- Pride and Prejudice (B1+) — Austen’s long sentences are built on stacked relative clauses. Her opening line alone shows the structure.
- Dracula (B1+) — Stoker’s journal-style writing chains relative clauses to describe places, people, and events that connect across the narrative.
- The Picture of Dorian Gray (B1+) — Wilde’s epigrammatic style relies on relative pronouns to layer modifiers onto modifiers, creating his characteristic prose rhythm.
Where you'll see this in books.
It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife. However little known the feelings or views of such a man may be on his first entering a neighbourhood, this truth is so well fixed in the minds of the surrounding families, that he is considered the rightful property of some one or other of their daughters.
The artist who painted the portrait was Basil Hallward, whose work had captured something terrible. The studio where this happened was filled with the scent of roses. The painting that he created would change Dorian's life forever.
The man whom we had met in London was a friend of Mina's. The castle, which had stood empty for years, was now occupied. Jonathan, who had escaped from Transylvania, was finally safe.