Commas and Introductory Phrases

     Because he hated it when people came to his door Hermit Jones moved to an isolated cave in the mountains.

There is something missing from that sentence, and that something is a comma. It belongs between the introductory phrase and the rest of the sentence:

     Because he hated it when people came to his door, Hermit Jones moved to an isolated cave in the mountains.

How can you tell when a phrase is an “introductory phrase” rather than a normal beginning to a sentence? Well, first you need to know your basic sentence structure:

     SUBJECT      VERB     (sometimes optional) DIRECT OBJECT

        Callie           loves             those soft orange candy peanuts.

Most sentences begin with the subject of the sentence (and any adjectives used to describe them). If there is a complete phrase before the subject of the sentence, it is usually an introductory phrase that will need to be set apart by a comma. Introductory phrases usually describe the location, time, conditions, or reasons for the action taken by the sentence’s subject. So in our example above, Hermit Jones is the subject and moved is the verb. Everything before Hermit Jones is an introductory phrase describing his reason for moving, so it requires a comma to set it apart from the rest of the sentence.

Here’s some other examples:

      Before I get into the story, I should warn you that it is rather disturbing.

     Afraid of exposing herself to mockery, Dorothy decided not to try out for the cheerleading squad.

     To be perfectly honest, I don’t really understand the appeal of snowboarding.

     Lately, Georgina has seemed rather distressed and distant.

Now most of these examples have introductory phrases of several words, but take note of that last one. An introductory phrase can be as short as a single word. With such short introductory phrases, it isn’t uncommon to forgo a comma—I did it with “now” at the beginning of this paragraph, for example.

     Lately Georgina has seemed rather distressed and distant.

If you’re not sure whether or not it’s acceptable to leave out the comma between your short introductory phrase and the rest of the sentence, err on the side of caution and put the comma in.

The question of whether or not to include the introductory-phrase-comma is like the question of whether or not to bring food to a party: you might be okay if you don't, but you'll always be okay if you do.