Relative Pronouns
Use “who/whom/whose” chiefly for people, “which” for things and some whole-clause references, and “that” only in defining relative clauses. An object relative pronoun can sometimes be omitted in a defining clause, but a subject relative pronoun and pronouns in non-defining clauses cannot simply be dropped.
Relative pronouns introduce relative clauses. Common choices include “who,” “whom,” “whose,” “which,” and “that”; the right form depends on what the clause refers to, the pronoun’s grammatical role, register, and whether the clause is defining or non-defining.
Key details
Further guidance
Choice
Use “who” for people in ordinary subject/object roles, “whom” mainly in formal object/preposition contexts, “whose” for possession, “which” for things, and “that” for defining clauses only.
Clause Type
Non-defining relative clauses are set off as supplemental information and do not use “that” in the reviewed Cambridge framework.
Omission
You may omit an object relative pronoun in many defining clauses: “the book (that) I bought.” Do not omit a required subject relative pronoun: “the book that won.”
Worked Example
“The editor who called me” uses “who” as the subject of the relative clause. “The editor whom I called” is formal object use; “the editor I called” is also possible in a defining clause.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Relative pronouns (opens in a new tab)Cambridge University Press · Explains who, whom, whose, which and that by referent and relative-clause type, including omission and defining/non-defining restrictions.
- Relative clauses: defining and non-defining (opens in a new tab)Cambridge University Press · Cambridge distinguishes defining and non-defining relative clauses, their information roles, pronoun choices, and punctuation, providing the necessary boundary for an adjective-clause guide.