Style Guides Explained: Chicago, Ap, And Mla For Authors

Gary Smailes
Gary Smailes | 18 November 2025
Style Guides Explained: Chicago, AP, and MLA for Authors

Why Style Guides Matter in Book Editing

Style guides are not about fussiness. They are about trust. When your book follows a clear set of rules, readers relax. Editors breathe easier. Proofreaders move faster. Everyone reads from the same playbook.

What does a style guide cover? The unglamorous stuff that keeps a book clean. Punctuation. Capitalization. Numbers. Hyphenation. Citations. Manuscript formatting. The nuts and bolts that hold sentences together and keep pages consistent from chapter one to the acknowledgments.

Publishing has defaults. Book publishing leans on The Chicago Manual of Style, usually called Chicago or CMOS. Newsrooms and publicity teams use AP Style. Humanities scholars use MLA. If you are writing a trade book, fiction or nonfiction, choose Chicago unless your publisher tells you otherwise. For your website, press kit, and media pitches, build for AP. For an academic essay or a trade book with academic leanings, use MLA. Different venues, different rules, less friction.

Why this matters comes down to consistency. You do not want a list with an Oxford comma on page 12 and no Oxford comma on page 212. You do not want headline-style caps in one chapter and sentence case in the next. You do not want numbers spelled out in one paragraph and switched to numerals in the next for no reason. Readers notice patterns. They also notice when patterns break.

A quick example. The serial, or Oxford, comma.

Pick one approach and stick with it. Chicago prefers the first. AP often drops the final comma unless needed for clarity. Flipping back and forth makes a mess.

Another one. Title capitalization.

Choose based on your guide. Apply it to every chapter title, subtitle, and table heading.

Ellipses, en dashes, em dashes, and hyphens come with rules too. How many spaces around ellipses. When to use an en dash in number ranges. Whether to use spaced or unspaced em dashes. A guide settles these choices before you touch copyedits.

Pair your guide with a dictionary. You need one authority for spelling and hyphenation. For U.S. English, use Merriam-Webster. For U.K. English, use an Oxford dictionary. When a word looks odd, you look it up once, record the decision, and move on. Is it email or e-mail. Web site or website. Toward or towards. Decision made. No more debate in chapter eight.

Two quick stories from the trenches. I once edited a memoir with both okay and OK appearing dozens of times. We picked OK, logged it, and fixed the lot in an hour. Another time, a novel had US, U.S., and U.S.A. scattered across scenes. We chose U.S., set a search, and cleaned the book before design. Neither task is hard with a plan. Both are painful without one.

Make a plan now.

What belongs on your style sheet?

Mini exercise. Open a clean page and write Style Sheet at the top. Add the eight headings above. Now run a ten-minute scan of your latest chapter. Any word that gives you pause goes on the sheet with a decision. Do one chapter today. Your future edits will go faster.

A style guide is not a cage. It is a set of decisions that frees you from petty questions. Once the rules are set, your line edit can focus on voice and clarity. Copyediting can focus on precision. Proofreading can focus on the last stragglers that slipped through.

One last note. If you work with an editor, ask for their house style and share your style sheet. If you write across regions, decide on U.S. or U.K. English and record exceptions for character voice. A British character can say colour while the narration stays in U.S. spelling. Flag those choices so no one "corrects" the voice out of the scene.

Pick your guide and your dictionary. Start your style sheet. You will save hours. Your book will read cleaner. Your readers will feel the difference.

Chicago Manual of Style (CMOS) for Book Authors

If you write books, Chicago is your best friend. Trade fiction, memoir, narrative nonfiction, most self-published titles — they all live in Chicago territory. Publishing houses build their house styles around Chicago because it handles the complex formatting and citation needs that books demand.

Chicago works for books because it thinks like a book reader. Where AP style aims for speed and news consumption, Chicago considers how someone settles in with a 300-page story or follows a detailed argument across chapters. It balances precision with readability.

The Chicago Signature Rules

You'll recognize a Chicago-styled book by its hallmarks.

The Oxford comma. Always. "She packed books, pens, and notebooks." That final comma before "and" stays put. No exceptions, no second-guessing.

Em dashes without spaces. The long dash appears tight against the words it connects. "The weather turned cold—colder than anyone expected—and stayed that way for weeks." Not "cold — colder than anyone expected — and stayed." Clean and crisp.

Italics for book titles. The Great Gatsby, not "The Great Gatsby." Newspapers and magazines get italics too: The New York Times, Harper's Magazine. Articles and short stories get quotation marks: "A Good Man Is Hard to Find."

Headline-style capitalization. Chapter titles, section headings, and captions use headline style: "The Night the Power Went Out." You capitalize the first word, the last word, and everything in between except articles (a, an, the), conjunctions (and, but, or), and short prepositions (in, on, at) unless they start or end the title.

Spell out numbers one through one hundred. "She waited forty-seven minutes" not "She waited 47 minutes." For nontechnical prose, this keeps the text flowing without jarring numerals. Technical writing and scientific contexts get different rules, but for most books, words work better than digits.

Dialogue and the Human Voice

Chicago shines when it comes to dialogue and narrative voice. The rules for quotation marks, dialogue tags, and interior thoughts give you flexibility to serve the reader first.

American quotation style puts periods and commas inside closing quotation marks. "I'll see you tomorrow," she said. The comma goes inside the quotes even when logic suggests otherwise. Question marks and exclamation points follow sense: if the whole sentence asks the question, the mark goes outside. "Did she say 'I'll call you tomorrow'?" But if the quoted material asks the question, the mark goes inside. She asked, "Will you call me tomorrow?"

Interior thoughts get italics when rendered as direct thoughts: What am I doing here? he wondered. Or they stay in roman type when described: He wondered what he was doing there. Both work. Choose based on how close you want readers to feel to the character's mind.

Dialogue tags stay simple and functional. "I'll help," she said. Not "I'll help," she asserted. Chicago trusts "said" and "asked" to carry most conversations. The words in the quotation marks should provide the emotion and intensity.

Citations: Two Paths, One Destination

Chicago offers two citation systems. Pick early and stick with it.

Notes-Bibliography uses footnotes or endnotes plus a bibliography. Perfect for humanities writing, biography, narrative nonfiction, and any book where you quote extensively or need to provide context beyond basic attribution. The notes let you add commentary, cross-references, and detailed source information without cluttering the main text.

A typical note looks like this: David McCullough, 1776 (New York: Simon & Schuster, 2005), 45.

Author-Date uses in-text citations keyed to a reference list. Better for research-driven works, scientific writing, and books where you need to show a chronological development of ideas or compare studies across time periods.

A typical in-text citation: (McCullough 2005, 45).

Choose based on your book's needs and your readers' expectations. Humanities readers expect notes. Research and science readers expect in-text citations. Some publishers have preferences, so ask early if you're working with a press.

Building Your Chicago Toolkit

Get CMOS 17. The seventeenth edition. The online version updates more frequently than the print edition, but either works. Use the hyphenation table for compound words and the grammar sections for thorny usage questions.

Pair it with Merriam-Webster. Chicago defers to Merriam-Webster for spelling, so keep them aligned. The online version works fine and updates regularly.

Set up your style sheet sections. Add "Numbers" and "Capitalization" sections to track the edge cases. When you write "twenty-first century" vs. "21st century," log the choice. When you decide on "internet" vs. "Internet," record it. These small decisions compound across a book-length manuscript.

Sample some style sheet entries:

The Citation Decision

Make your citation choice before you draft your back matter. Notes-Bibliography requires a different approach to your research than Author-Date. With notes, you write as you go and compile the bibliography later. With Author-Date, you track sources in a reference manager and build citations as you write.

I've seen too many authors reach the final draft and realize they picked the wrong citation style. Converting from notes to in-text citations means rewriting every reference and changing how you present sources in the text itself. Do this work up front.

If you're unsure, default to Notes-Bibliography for most narrative nonfiction and memoir. The notes feel more natural to book readers and give you space to provide context without interrupting your story.

Chicago is not perfect. It's comprehensive, which makes it sometimes overwhelming. But for books, it works because it anticipates the complexity of book-length writing. Unlike news writing or academic papers, books develop ideas across chapters, reference multiple types of sources, and need formatting that supports sustained reading.

Set up Chicago early. Learn its signature moves. Build your style sheet around its framework. Your book will read like a book, not a collection of blog posts or academic papers. That matters more than you might think.

AP Style for Author Platforms and Publicity

Your book follows Chicago, but your publicity materials need to speak AP. This isn't about being picky — it's about making journalists' lives easier so they'll use your content.

When you send a press release to a newspaper or magazine, the editor shouldn't have to reformat your dates, fix your comma usage, or change your numbers from words to numerals. They should copy, paste, and publish. AP style makes that possible.

Where AP Rules Your Writing

Author bios for media kits. The 150-word biography that goes to journalists, podcasters, and event organizers needs AP formatting. Not the bio in your book's back matter — that stays Chicago.

Press releases. Every announcement about your book launch, awards, speaking events, or media appearances. AP style tells journalists this content comes ready to use.

Website announcements and newsletters. When you're writing for broad audiences and quick consumption, AP's clarity and brevity serve readers better than Chicago's more formal approach.

Guest posts for magazines and newspapers. Online publications, especially those with news backgrounds, default to AP. Submit in their preferred style.

Social media captions for professional announcements. While casual social media posts follow no particular style, professional announcements about your work benefit from AP's conciseness.

The Key Differences That Matter

Drop the Oxford comma. In AP style, you write "She studied fiction, memoir and poetry." The comma before "and" disappears unless it prevents confusion. "He thanked his parents, Einstein and Gandhi" needs that final comma to show Einstein and Gandhi aren't his parents. But most of the time, no comma.

Use numerals for 10 and above. Write "She waited 47 minutes" not "She waited forty-seven minutes." Numbers one through nine stay as words: "She had three books." This makes information scannable for news readers.

Keep sentences concise and direct. AP favors shorter sentences and active voice. Instead of "The novel, which took her five years to complete, explores themes of family and belonging," write "The novel explores family and belonging. She spent five years writing it."

Downstyle capitalization. Job titles get lowercase unless they appear before names: "author Jane Smith" but "Jane Smith, author." Geographic regions stay lowercase: "She grew up in the south." Seasons stay lowercase: "The book releases next spring."

Specific date and state formats. Dates look like this: "March 15, 2023." States get abbreviated when they appear with city names: "She lives in Portland, Ore." Some states never get abbreviated: Alaska, Hawaii, Idaho, Iowa, Maine, Ohio, Texas, Utah.

Titles and Online Formatting

AP treats composition titles differently than Chicago. Most books, movies, TV shows, and songs get quotation marks, not italics: She wrote "The Memory Palace." Reference works like dictionaries and encyclopedias get italics, but your novel doesn't.

This matters online where italics don't always display consistently across platforms. Quotation marks work everywhere.

Headlines get straightforward treatment. No clever wordplay or literary allusions. "Local Author Wins National Book Award" beats "Dreams Take Flight: Local Writer Soars to National Recognition." Save the creativity for your book's prose.

Speed and Journalist-Friendly Copy

AP exists to help reporters work fast. When you format a press release in AP style, you signal that you understand media workflows. Editors see clean copy that fits their publication without extra work.

Consider this Chicago-style sentence: "The award-winning author, who has written three novels over the past fifteen years, will speak at the university's annual writers' conference this fall."

Here's the AP version: "The award-winning author will speak at the university's annual writers' conference this fall. She has written 3 novels over the past 15 years."

The information stays the same. The presentation becomes faster to read and easier to edit.

Maintaining Two Versions

Keep a Chicago author bio for your book's back matter and an AP version for media outreach. They serve different audiences and contexts.

Chicago bio excerpt: "Sarah Chen writes literary fiction that explores the intersection of family loyalty and personal ambition. Her debut novel, The Weight of Expectations, won the 2023 Regional Fiction Prize. She has published short stories in Prairie Schooner, The Georgia Review, and Glimmer Train. Chen holds an MFA from the University of Iowa and lives in Portland, Oregon, with her family."

AP bio excerpt: "Sarah Chen writes literary fiction exploring family loyalty and personal ambition. Her debut novel, "The Weight of Expectations," won the 2023 Regional Fiction Prize. She has published short stories in Prairie Schooner, The Georgia Review and Glimmer Train. Chen holds an MFA from the University of Iowa and lives in Portland, Ore., with her family."

Notice the changes: no italics for the novel title or magazine names, no Oxford comma in the magazine list, abbreviated Oregon, and slightly more direct phrasing.

Store both versions in your style sheet. Update them together when your biography changes.

Building Your AP Toolkit

Get AP Stylebook Online. The digital version updates continuously and includes a search function for quick checks. The print edition goes out of date too fast for regular use.

Create press release templates. Standardize your dateline format, contact information layout, and boilerplate language. A template prevents style errors when you're rushing to announce news.

Sample dateline: "PORTLAND, Ore., March 15, 2023 — Local author Sarah Chen announced today..."

Practice numbers and dates. Write "10 a.m." not "10:00 a.m." Write "March 15" not "March 15th." Write "the 1990s" not "the 1990's." These small details signal professional media awareness.

Learn state abbreviations. AP uses specific abbreviations that don't always match postal codes. California becomes "Calif." not "CA." Massachusetts becomes "Mass." not "MA." Get the list and keep it handy.

The Professional Advantage

Publishers' publicity departments use AP style for their press materials. Literary agents write query letters in AP style when they pitch to media contacts. Book reviewers at newspapers and magazines expect AP formatting in the materials they receive.

When you follow AP for publicity, you align with industry standards. Your press releases look professional. Your media kit matches what publicists create for major authors. Journalists take your announcements seriously because they look like they came from someone who understands media.

This isn't about abandoning Chicago for your creative work. Your manuscript stays Chicago. Your book's formatting follows Chicago. But when you step into the publicity arena, you switch to the language that arena speaks.

Think of it as code-switching for writers. You speak one way in your novel and another way in your press release, just like you speak differently at a dinner party than you do in a job interview. Both voices are professional. Both serve their purposes. The key is knowing when to use which one.

Set up your AP templates now, before you need them. When your book wins an award or you land a speaking gig, you'll want to announce it immediately. Having AP-ready templates lets you move fast while maintaining professional standards.

MLA Handbook Basics for Authors Who Cite Sources

Writing for a scholarly-leaning audience? Use MLA. It suits essays in the humanities, academic-flavored articles, and trade books that rely on in-text citations plus a Works Cited list. If your readers expect to see author and page in parentheses, you are in MLA territory.

How MLA Works

MLA uses a simple pair. A brief in-text citation points to a full Works Cited entry.

Readers move from your sentence to the parenthetical note to the Works Cited entry without friction. That is the goal.

Quick examples in your prose:

Period goes after the parenthetical. Commas and periods stay inside the closing quotation mark in American English.

Works Cited, Built from Containers

MLA thinks in containers. A chapter can live inside an edited book. A poem can live inside an anthology. An article can live inside a journal. You name the thing you used, then the container that holds it, then any second container such as a database.

The core template looks like this:

Author. Title of Source. Title of Container, other contributors, version, number, publisher, publication date, location.

Not every field applies. Use what you have. Keep the order. Use title case for titles. Italicize containers. Use quotation marks for sources that are part of a larger whole.

Examples you can model:

Formatting habits to lock in:

Quoting, Paraphrasing, and Staying Safe

You have two jobs. Represent the source clearly. Keep your permissions clean.

Style Tendencies in MLA

These choices give MLA its look.

A quick before and after:

Avoid Rework, Ask Early

Action: confirm publisher preference. Some trade presses want Chicago notes and bibliography even for humanities topics. Others accept MLA without complaint. Ask before you build appendices, notes, and a Works Cited. Converting at the end wastes time and frays nerves.

Tools and a Simple Workflow