Who vs. Whom

Some people think the main difference between who and whom is the way they sound, with whom being the more formal way to say who. In reality, the distinction between them is grammatical. Even though who and whom are both pronouns, they do completely different jobs in a sentence—who acts as the subject while whom acts as the object. Just remember to use who to refer to the person who is propelling the action in a sentence; use whom when the person is having the action done to them. You also use whom, never who, as the object of a preposition.

Who	Whom1
Subject pronoun	Direct or indirect object pronoun
Never use as the object of a preposition	Must use with prepositions

Let's look at some examples:

Students who study hard usually earn excellent grades.
The pronoun, who, is referring back to the subject, students. (Who earns excellent grades? The students do.) Because the pronoun is referring to a subject, it would be incorrect to use the object pronoun whom.

Earning excellent grades also depends on whom you study with.
This sentence has two clauses, but for the purposes of this lesson we'll focus only on the second one, whom you study with. In this clause, whom is the object of the preposition with, so it would be incorrect to use the subject pronoun who.

A Couple of Sticky Situations

There are certain sentence types that make it difficult to decide whether to use who or whom.

• Object of One Clause, Subject of Another

  This situation involves two verbs with a pronoun between them:

  It was pitch dark, and I couldn't see who was coming down the hall.

  Notice how who seems to "stick" to both verbs—it looks like the object of the first verb and the subject of the second. So which pronoun do you choose, who or whom? There's a simple answer—subjects speak louder than objects because they propel the action in a sentence, so always "stick" with the subject pronoun who.

• Preposition Separated from its Object

  Take a look at this example of traditional formal English:

  For whom are those flowers?

  Chances are you've never heard anyone ask a question that way. When we talk, the preposition "unsticks" from the pronoun and moves all the way down to the end of the sentence:

  Whom are those flowers for?

  Still sound strange? That's because most people would say Who are those flowers for? but it's really better to use whom because it's the object of the preposition for.

  It's easy to tell when you're dealing with an object-preposition separation because you can replace whom with him, her, me, us, them, etc.

  Question: Whom are those flowers for?
  Whom is the object of the preposition for.

  Answer: The flowers are for her.
  Now, in the answer, her has become the object of the preposition for.

  Note:

  Traditionally, it is incorrect to end a sentence with a preposition, but when we talk it happens naturally. Many teachers still prefer their students not to end sentences with prepositions, but this rule has become more relaxed in recent years.