Use who when the person is doing the action, and whom when the person receives it or follows a preposition in formal English: “Who called?” but “Whom did you call?” The handy test is to replace the word with he or him. If he fits, use who; if him fits, use whom. [1]
Find the person’s job in the clause
In “Who sent the invitation?” the unknown person performs the action of sending, so who is the subject. In “Whom did the organizer invite?” the organizer performs the action and the unknown person receives it, so whom is the object. The question word’s place near the beginning does not determine its form; its role in the clause does.
Try the substitution: “He sent the invitation,” so who works. “The organizer invited him,” so whom works. Purdue OWL describes who as the subject form and whom as the object form, with this he/him check as a practical memory aid. [1]
Look inside embedded questions
The same distinction applies when the question sits inside a larger sentence. In “I know who sent the invitation,” who is still the subject of sent. In “I know whom the organizer invited,” whom is the object of invited. The words before the clause do not change that internal role.
A common trap is choosing by the nearest verb. In “The editor asked who the poet had thanked,” the poet is the subject of had thanked; the person thanked is its object. The substitution is “the poet had thanked him,” so whom is called for in formal writing: “The editor asked whom the poet had thanked.”
Prepositions make the object visible
After a preposition, formal prose typically uses whom: “To whom should I send the draft?” and “With whom did you rehearse?” The preposition to or with introduces an object, which is why whom fits. In a more conversational style, many speakers put the preposition at the end and use who: “Who should I send the draft to?” That form is widely used and sounds natural in many settings.
The choice can signal tone. “To whom it may concern” is conventional and formal; “Who is this for?” is ordinary conversation. Neither phrasing is automatically better in every context. Consider the audience, the level of formality, and whether a more direct sentence would be clearer.
A two-line editing drill
Imagine writing an event note: “Who should receive the recording?” and “Whom did the host thank?” For the first, answer “She should receive it”: who is the subject of should receive. For the second, answer “The host thanked her”: whom is the object of thanked. The pronoun substitution gives a quick check without requiring you to label every part of speech.
Now try: “The person who/whom we invited will introduce the speaker.” Rebuild the clause: “We invited him.” Since him fits, formal edited prose favors whom. But the sentence can be recast to avoid a fussy choice: “Our guest will introduce the speaker.” Rewriting can improve rhythm when the who-or-whom decision is distracting.
A note on usage and register
Who and whom form a distinction in standard formal English, but everyday usage is not always as tidy as a grammar exercise. Who is common in conversation where traditional rules would prescribe whom, especially when the word begins a question or follows a preposition at the end of a clause. In a formal document, a writer may choose the traditional object form; in speech or informal writing, who can sound more natural.
A practical approach is to use the role test when editing for formal contexts, then read the sentence aloud. If whom makes the line awkward, try moving the preposition or rewriting the clause. Clarity and tone both matter; the purpose is to make the relationship between people and actions easy to follow.
