Should I use a comma at the end of a quotation, before the closing quotation mark?

In American English, you should always place a comma or period inside quotation marks. In UK usage, you can choose. Most style guides, such as the Modern Language Association (MLA), Associated Press (AP), and The Chicago Manual of Style (Chicago) suggest the American rule. If you're uncertain who your audience will be then it's best to always place your commas inside of quotes. That way you'll never been seen as wrong.

• Correct: "I'll come along later," said Mary.
• Incorrect in US: "I'll come along later", said Mary.
• Incorrect in US: "I'll come along later" said Mary.