Use the pronoun who to refer to the subject of a verb and the pronoun whom to refer to a verb’s object or to the object of a preposition:

Who wants to go on vacation?

I don’t know whom to tell.

To whom should I give the book?

In the examples above, who is the subject of the verb wants, the first whom is the object of the verb tell, and the second whom is the object of the preposition to.

But beware of tricky constructions. In the following example, should you use who or whom?

The neighbor _____ they wanted to invite was out of town.

Here you should use whom because it is the object of wanted to invite. If you are unsure, you can rearrange part of the sentence as a test: they wanted to invite whom.

Here’s another example where rearranging the sentence can be helpful:

Is there someone _____ I can help?

Here the correct term is whom because it is the object of can help: I can help whom? You could also try substituting a personal pronoun. Would you say I can help she? No, you would say I can help her. Her and whom are both object pronouns, so if the sentence makes sense with her, then you should choose whom.

Let’s try another one:

The woman returned the toy to the child _____ she assumed had lost it.

Here the correct term is who because it is the subject of had lost. To test, try removing she assumed from the sentence: The woman returned the toy to the child who had lost it.

Finally, keep an eye out for verbs followed by prepositions. Which of the following sentences is correct?

There’s no accounting for who loves you.

There’s no accounting for whom you love.

Trick question! Both are correct. The key is to determine how the pronoun relates to the verb. In the first example, who is the subject of the verb loves. In the second example, whom is the object of the verb love. 

Think you understand the difference between who and whom? If so, test your knowledge with our quiz.

For more on pronouns, see our Grammar Topics page.