Does an introductory clause or phrase need a comma after it?

"Does an introductory clause or phrase need a comma after it?"

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It is appropriate to use a comma after an introductory a) clause, b) phrase, or c) word that comes before the main clause:

a) Because it was snowing, the flight was delayed.

b) Having completed her work, she went to bed.

c) Yes, you should eat a healthy breakfast.

Use a comma to set off an introductory clause beginning with these frequently used words: after, although, as, because, if, since, when, while.

Use a comma following an introductory phrase that includes: infinitive and participle phrases, nonessential appositive phrases, absolute phrases,and long prepositional phrases.

A comma should be used after an introductory prepositional phrase to avoid misreading: In all, four students failed the class.

In addition, single introductory words should also be followed by a comma: however, well, yes, unfortunately, etc.

W.W. Norton lists a stylistic exception: "To accelerate the pace of their sentences, writers sometimes skip the comma after an introductory adverb or short introductory phrase" (p. 455).

See Also

"Commas After Introductory Clauses and Phrases" (video)

"Using a Comma After an Introductory Element" (video)

External Links

APS Online Style Manual

Purdue OWL