CMoS Summary - Comma Rules

Greetings from the Hermit WRiter.

Everyone is an expert in commas. Every reader senses where a pause is required, or effective. It's subjective. Many commas are optional (fall under 6.18, below). If the writer doesn't want to pause in order to build tension, rip out those commas. But leave out one required, such as in dialog addresses, and you look like an amateur. 

There are about seven major sources of expertise in grammar. (Take note, the experts disagree.) Here is a summary of what one says on the matter, from The Chicago Manual of Style:

• To separate clauses joined by and or but.

• To separate a series of things or actions.

• Before and after the names of people you’re talking to.

• Before or after a quotation.
• After an introductory phrase if a pause is intended.
• Around an aside.

• Around which clauses, but not that clauses.

 And a little of the specifics:

6.18 A comma indicates a pause, involves judgment with ease of reading the goal

6.19 Use comma in a series: John, Jack, and Rick ran

6.20 Leave out comma in series where each separated by conjunction 

6.21 Use semicolon with complex lists, or those containing punctuation

6.22 Surround “etc.” and clauses like “and so forth”: X, y, z, and so forth, were…

6.23 “Et al” does not require a comma

6.24 No comma with use of Ampersand in names

6.25 Use with introductory clauses when a pause is intended

6.26 No comma if introductory clause immediately followed by verb it modifies

6.27 Commas follow “oh” or “ah” when a pause is intended

6.28 Commas always follow direct address: Joe, do you…

6.29 Commas follow words like “yes,” “no,”

6.30 Commas set off parenthetical elements

6.31 Restrictive clauses, those essential to the meaning of the noun it belongs to, should NOT be set off by commas: The woman wearing the red coat…; Nonrestrictive clauses should be separated: My sister, wearing the red coat,…

6.32 Commas usually precede conjunction, except when clauses are short or closely connected

6.33 Include comma before conjunction in a series of independent clauses making up a list connected by conjunctions: Noun verb, noun verb, noun and noun verb 

6.34 Compound predicate: one subject, multiple actions—comma is optional; depends upon readability 

6.35 Preceding dependent clause requires comma: If you accept, we shall…

6.36 Trailing dependent clause, comma depends upon readability, if writer wishes a pause: We agree if you accept…

6.37 And if, but if, that if—Conjunctions side-by-side should NOT be separated by comma unless pause needed for readability

6.38 See 6.31—Clauses essential to the meaning of a sentence are not separated by commas; dependent clauses are separated: The report the committee submitted was… BUT: the report, which was well documented, was…

6.39 Adjective series should be separated by comma unless adjective closest to subject are conceived as a unit (political science)

6.40 Repeated adjectives are separated by a comma: Bad, bad dog

6.41 “Not,” “Not only”-like interjecting clauses require commas if pauses are intended; if separated, both ends of clause must be covered with commas

6.42 Longer comparative phrases should be separated by commas, but may be left off shorter: The more the merrier; The sooner the better

6.43 See 6.31, 6.38—Nonessential phrases, which include supplementary information, should be separated by commas: Committee chair, Gloria Ruffolo, called…

6.44 “That is” type of expressions are usually separated (comma, em dash, semicolon, parens): The compass stand, or binnacle, must be…

6.45 Separate homonyms, except “that that,” by commas: Whatever is, is good

6.46 Dates—Separate year in MDY format; not required in D-M-Y format or M-Y or free-standing year, such as: Thanksgiving Day 1999

6.47 Addresses—Separate individual elements (city, street & number, state), but not abbreviations

6.48 See 6.31, 6.38, 6.43—Personal names & place names: Separate only when nonessential: The Kennedys of Orange County

6.49 Commas do not separate “Jr.” “Sr.” or enumerations (II, III)

6.50 Commas do not separate “Inc.” “Ltd.” and the like

6.51 – 6.56 are irregular usage and thus left out of this summary

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