The Grammar of Dialogue
Grammar is one thing. You learn it in elementary school, forget it in middle school, and then painstakingly re-learn it in high school. Grammar within dialogue is another thing. Most schools don't teach it, which can make it a challenge for the beginning writer. This is how to get to the bottom of all the commas and capitalization.
Spoken Words > Dialogue Tag
"This is cool," said John.
The spoken words are (obviously) encased in quotation marks, and ended with a comma, also inside the quotation marks. The "said" is not capitalized. It can also be written as, 'John said', in which case, John would be capitalized, as it is a proper noun. Note that the order of the name of the speaker and the "said" word are not always reversible.
Spoken Words > Dialogue Tag > More Words
"I know," said Matt. "Isn't it great, Mary?"
The first part is identical to the "Spoken Word > Dialogue Tag". The second part is ended with a period, question mark, or exclamation point, depending on context.
Part of Spoken Words > Dialogue Tag > Rest of Spoken Words
"This is," said Mary, "the stupidest thing I have ever seen. You two are idiots."
When the dialogue tag breaks up a single sentence, a comma is used after the dialogue tag or name of the speaker (whichever comes last), and the first word of the second part of the sentence begins is not capitalized (unless it's a proper noun). If you're confused, ask yourself this: Could the words before and after the dialogue tag stand as their own sentences? If the answer is no, then you use this.
Action > Spoken Words
Sam set down the mug. "I wish."
If the action should not lead into the dialogue in any way, it simply ends with a period and the dialogue begins on its own.
(Action) > Dialogue Tag > Spoken Words
(Mark tossed his empty cup into the trash can.) He said, "Let's ditch. This party's getting boring."
Whether or not the action is there, the comma after the "said" remains. This is a time when the "said" word must immediately precede the spoken words.
Action Transitioning to Dialogue Tag > Spoken Words
With a half-hearted smile, Kim said, "Well, there're plenty more fish in the sea."
Kim gave a half-hearted smile, saying, "Well, there're plenty more fish in the sea."
If the wording of the action depends on the dialogue tag following it, end it with a comma.
Now onto a similar subject: Thoughts. There is no officially correct format for thoughts, but common examples include:
- This must be it, he thought. (Normal text)
- "This must be it," he thought. (In quotation marks)
- This must be it, he thought. (In italics)
- "This must be it," he thought. (Italicized and in quotation marks)
Whatever you choose, just make sure it's easy to distinguish thoughts from spoken words. Treat thoughts as normal dialogue in all other aspects.