The key question when trying to determine correct pronoun case is: Is the pronoun the subject of a verb? For example:

 Hannah and I found a new store at the mall.

In this sentence, the pronoun “I” is used correctly because, along with Hannah, it’s a subject of the verb “found.” So the subject case is used.

Compare the pronouns in this next sentence:

Between you and me, the seller is asking for too much money.

Here, the pronoun “me” is also used correctly. “Me” is not the subject of a verb. “Me” is part of the phrase “between you and me” and thus “me” is correctly in the object case.

So with that basic rule in mind, you can quickly see which sentences use the correct pronoun case and which do not. As usual, your grammar checker can help out by flagging potential errors with a green squiggly line. If you right-click on the line, the grammar checker will suggest the correct pronoun case. For instructions on how to set up your word processor's spelling, grammar and style checker, see: http://polaris.umuc.edu/ewc/web/checkers.html

If you are having difficulty determining the proper case of a pronoun, and the grammar checker is not of any help, another option: is to revise the sentence. For example:

 There is a rumor about everyone’s on the team wanting to quit.

Here the possessive pronoun “everyone’s” will not be flagged by the grammar checker, but still seems confusing. One option is to revise the sentence in a way that you are sure the pronoun being used is correct. For example, we could easily revise this sentence to read:

 According to a rumor, everyone on the team wants to quit.

When you try to understand pronoun case, look to see if the pronoun is a subject of a verb and remember that the grammar checker may not flag all possible problems. When in doubt, simply rewrite the sentence so that you are sure your pronouns are clear and correct.