Who's on first? When to use who vs. whom is a grammar issue that stumps a lot of people, but it's really not that difficult if you know the rule. Use who when you are referring to the subject of a clause and whom when you are referring to the object of a clause. The subject is the one doing the action, and the object is the one having the action done to them. Ex: Paul hit Allan. In this sentence, Paul is the subject and Allan is the object. Now that you understand that, I'll give you a short-cut way to figure it out. He = Who and Him = Whom. If you would use 'he' in the sentence, then use 'who.' If you would use 'him,' then use 'whom.' Who hit Allan? (He hit Allan.) ...Paul hit whom? (Paul hit him.) While we're on the topic of subjective and objective pronouns , let's touch on some problems with them. First, I'll give you a list of each. Subjective pronouns are used when they are the subject of the sentence. They are I,...