As a tutor in the EIU Writing Center, I’ve seen quite a few grammatical concerns that repeatedly show themselves. Perhaps the single most common I’ve seen, the one that crops up not only in the writing of students who visit the Center, but in my own writing (and even my professors’), is what we call the Comma After an Introductory Element.
The Writing Center Resources for Writers page has a link to a marvelous comma handout, the entire first section of which deals with this issue. What I’m going to attempt to do here is break down the issue into something that is easily understandable. Think of this as the CliffsNotes version.
An Introductory Element is basically a word or phrase at the beginning of a sentence that sets up one of the following questions: where, why, when, how, or in what manner. There are certain key words that indicate one of these phrases is about to appear; common ones include “in,” “when,” “because,” “if,” “although,” “since,” or words ending in –ing. Let’s look at an example sentence, without proper punctuation:
On the day following her exorcism Reagan felt immensely relieved.
Let’s start at the beginning of this sentence. We have the word “on,” which immediately sets up a “where/when” scenario. In this case, it’s “when.” So we know immediately that we’re going to have a comma coming our way.
But where does it go? Let’s look for our subject. Who is doing something in this sentence, or having something done to them? The answer is Reagan—this sentence is about Reagan feeling relieved.
So now we know that the word “on” is referring to when Reagan felt relieved. And when was this? “The day following her exorcism,” of course! So now that we have an answer to our question, we put in our comma:
On the day following her exorcism, Reagan felt immensely relieved.
A shorthand way to think of this is: 9 times out of 10, the comma will go immediately before the subject of the sentence. Thus, since Reagan is our subject, the comma goes before her.
I recommend checking out the linked handout for further examples, or even picking up a copy from the Writing Center. This is a tricky issue that even the most experienced writers face, so there’s no shame in asking for some help with it.