1/2008
3. Introductory Elements
To prevent misreading, use commas to set off common introductory elements from the main part of the
sentence:
Dependent Clauses, which begin with subordinating conjunctions (e.g., when, since, after,
although).
Example: When I was a child, I liked to ride my bike.
Example: Although Susan called, John did not get the message.
Infinitive Phrases, Long Prepositional Phrases, and Participial Phrases
Example: To tell the truth, we made the wrong decision.
Example: Before the important business meeting, she had to make her own coffee.
Example: Arriving very early for work, she found the parking lot empty.
Note
: No comma is needed if the introductory phrase is short and closely related to the main clause,
and the meaning is clear.
Example: After dinner we left.
Conjunctive Adverbs when placed at the beginning of a sentence (e.g., however, indeed,
furthermore, therefore).
Example: However, I also like to watch television.
Example: Furthermore, he wanted action to take place by next week.
4. Compound Sentences
Use a comma to separate the independent clauses in a compound sentence:
Example: The snow started to fall heavily, so all the schools and universities
closed early.
The comma is optional if both independent clauses are short and the meaning is clear.
Example: John is tall so he ducks when entering rooms.
Note
: When the same subject is doing both actions (a compound verb but not a compound sentence), do not
use a comma.
Example: She skips and runs down the sidewalk.