When you ask writers what words give them trouble, whom and who almost always make the list. It’s no wonder — there are some complicated grammar rules that govern when to use whom or who.

But with a simple trick, you can make sure you always get it right.

The Grammar Rules

Who is used when it’s the subject of a verb or the complement of a linking verb. Here’s an example: Who ruined the keyboard? It was Elliot who spilled the glass of water on it.

In the first sentence, who is the subject. The second sentence is a little trickier. First, find the verbs in the sentence — in this case they’re was and spilled. Then pick out their subjects: Elliot and who. Who is the right choice because it’s a subject.

Whom is used as the object of a verb or preposition. For example: You told whom to write the article? (Object of the verb told.) Or: George is the one to whom I was speaking. (Object of the preposition to.)

One exception is when you have a prepositional pronoun that’s also a subject. In this situation, the correct choice is who: I didn’t know either team, so I cheered for who had the brightest uniforms.

The Trick

If you’re not sure whether to use who or whom, try replacing it with he or him.

• If he sounds better, use who.
• If him sounds better, use whom.

Note: You may have to split the sentence for it to make sense. Now, try this trick with the previous examples:

Who ruined the keyboard?
He ruined the keyboard?

It was Elliot who spilled the glass of water on it.
It was Elliot. He spilled the glass of water on it.

You told whom to write the article?
You told him to write the article?

Finally, here’s what to do if you’ve tried everything and you’re still not sure when to use whom or who: don’t sweat it. Just rework the sentence so it doesn’t include either word, and get on with your writing.