The correct use of pronouns is a problem for many writers. Your pronouns must agree with the nouns that precede them (called the antecedents of the pronouns).One of the causes of this difficulty is understanding the use of pronouns in gender-neutral or gender-specific situations (see the Using Gender-Fair or Neutral Language page if this is your concern).
There are two types of agreement that must be correct: agreement in person and agreement in number. If you are wondering when to use "I," "you," or "he," "they," etc., please see the What is Person? page of this chapter. This page will discuss maintaining pronoun-antecedent agreement in number and clarity in your sentences when you use prounouns.
NUMBER AGREEMENT: This seems like a no-brainer: if you use a singular noun, use a singular pronoun; a plural noun, a plural pronoun. You should be aware of some complicating factors, however.
Despite the fact that several of these words may seem to refer to zero people or things or multiple people or things, grammatically all of these words are singular, and will only take "he," "she," or "it" for pronouns.
You can see the awkwardness this situation can cause; this is where a review of Gender-Fair and Neutral Language may be useful.
PRONOUN CLARITY: there are several situations which commonly cause problems -- see if any of these apply to your writing.
You may not think that looks correct, but it is; we do not use "her" here because the word "she" completes the meaning of the subject "it."
Sounds odd, right? Well this is correct, because both "him" and "me" are in the objective case in this situation (they are being acted upon by the actor in the sentence and the verb). Thus, you know that if you hear "Walter called he and I into the room," that is incorrect. The easy way to avoid the odd sound here is to say "us," but be aware of this problem in other situations.
EX: Reflexive: I hit myself in the head with the ball.
Intensive: You can wash your muddy dog yourself!
EX: NO: Jordan called Joel and myself.
YES: Jordan called Joel and me.
EX: I love the Spice Girls and chili cheese dogs --they're so hot!
Is this a comment on your musical or culinary taste?
EX: Monica told Sheila to pick up her brother at three.
What if Monica and Sheila both have brothers?
Another problem situation occurs with the pronouns "this," "that," "it," etc., often at the beginning of a sentence:
EX: The poetic diction of Shelley is the most difficult aspect of "Kubla Khan." This shows his greatness.
There is no set rule to solve this problem in every unique situation, but remember the following:
The Spice Girls are my favorite singers and chili cheese dogs are my favorite food!
Monica asked Sheila to pick up her brother Steve. (Assuming that only one of them has a brother named Steve.)
Monica said her brother Steve would be ready at three so Sheila could pick him up.
AVOIDING THE PROBLEM ALTOGETHER
The real issue here, however, is that you are proofreading carefully and thinking about how your words sound to someone else not as familiar with your topic. This practice will help eliminate these problems (notice how I used two nouns in this sentence to avoid problems with "this" and "these"). When you are proofing the paper, try circling the pronouns and drawing arrows back to the nouns to which they refer as a check on yourself.