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Using Commas After Introductory Elements

written by: Keren Perles • edited by: Donna Cosmato • updated: 2/14/2012

The third rule of comma use concerns using commas after certain introductory clauses. In short, use commas after dependent clauses, long prepositional phrases, and other introductory phrases.

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    Dependent Clauses

    The most often-cited example of an introductory element that requires a comma is the dependent clause. Dependent clauses are groups of words that contain a subject and verb and begin with a subordinating conjunction. Here are some examples of dependent clauses:

    • before Matt and Amy got to school that day
    • because they found a hundred dollar bill on the sidewalk
    • although the soldiers were weary from the long day of fighting

    If these clauses come at the end of a sentence, no comma is necessary. For example:

    • The class prepared for the party before Matt and Amy got to school that day.
    • The sisters became rich in a day because they found a hundred dollar bill on the sidewalk.
    • The generals decided to march through the night although the soldiers were weary from the long day of fighting.

    When the clauses come at the beginning of the sentence, however, they are introductory. Therefore, you should put a comma after them.

    • Before Matt and Amy got to school that day, the class prepared for the party.
    • Because they found a hundred dollar bill on the sidewalk, the sisters became rich in a day.
    • Although the soldiers were weary from the long day of fighting, the generals decided to march through the night.
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    Long Prepositional Phrases

    Introductory prepositional phrases that are three words long or fewer do not require a comma after them. For example:

    • In the tree a monkey sat and looked around.
    • After recess the class filed back into the classroom.
    • In Lakeside nobody swims in the summer.

    Introductory prepositional phrases that are longer than three words, however, do require a comma after them. For example:

    • In the tree near the running river, a monkey sat and looked around.
    • After morning recess for 5A, the class filed back into the classroom.
    • In Lakeside in the summertime, nobody swims in the lake.
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    Other Introductory Elements

    You can put a comma after many other phrases that introduce the first clause of the sentence. Although you can omit the comma if the introductory phrase is short and the omission will not cause confusion, you should use the comma if there is any doubt about its necessity.

    Here are some examples of other introductory elements that can end in a comma:

    • On the other hand, nobody forbade him from going.
    • Racing to the lunch table, he tripped over a knapsack and went sprawling.
    • To skateboard well, you need to spend a lot of time practicing.

When to Use Commas: A List of Comma Rules

Confused by commas? These rules for comma usage will teach you how and when to use commas. Includes information about items in a series, introductory phrases, and comma splices.
  1. Using Commas in a Series: Basic Rules
  2. Using Commas Between Independent Clauses
  3. Using Commas After Introductory Elements
  4. Using Commas With Non-Essential Elements
  5. Miscellaneous Rules of Comma Usage