Apostrophes and Hyphens: Rules, Common Mistakes, and How to Use Them Correctly

Apostrophes and hyphens are two of the most frequently misused punctuation marks in English. Apostrophes show possession (Sam's book) or form contractions (don't, it's). Hyphens join words into compound modifiers (well-known author) and connect prefixes to certain root words (self-respect, anti-inflammatory). This guide explains every rule, the exceptions, and the mistakes that show up most often in professional writing.

Apostrophes and Hyphens: At a Glance

What Is an Apostrophe?

An apostrophe is a punctuation mark with two main functions in English writing. It shows that something belongs to someone or something (possession), and it marks where letters have been omitted when two words are combined into one (contractions). Understanding both functions resolves most everyday apostrophe questions.

How to Use Apostrophes for Possession

To show that something belongs to a person or thing, add an apostrophe and an "s" after the noun.

• Sam's book means the book belongs to Sam. Sam's book is on the table.
• The cat's toy means the toy belongs to the cat. The dog is playing with the cat's toy.
• The children's playground means the playground belongs to the children. I heard laughter from the children's playground.

Singular Possessive

For singular nouns, add 's to show possession. This rule applies even when the singular noun already ends in "s," though some style guides allow exceptions for proper nouns.

• The cat's toy (one cat). The cat's toy is in the corner by the dog's bone.
• James's car (belongs to James). I left my coat in James's car.
• The boss's office (one boss). The meeting is in the boss's office at 10 a.m.

Plural Possessive

For plural nouns that already end in "s," add only an apostrophe after the "s." For irregular plurals that don't end in "s" (children, women, people), add 's.

• The cats' toys (multiple cats). The cats' toys are scattered across the living room.
• The Smiths' house (the family named Smith). We went over to the Smiths' house yesterday.
• The women's department (irregular plural). The women's department is on the second floor.

Pro tip. For singular proper nouns ending in "s" (James, Charles, Davis), Chicago Manual of Style recommends adding 's (James's, Charles's). AP Stylebook recommends only an apostrophe (James', Charles'). Both are acceptable. Be consistent within a single document.

How to Use Apostrophes for Contractions

An apostrophe replaces the missing letter or letters when two words are combined into a contraction. Contractions are widely accepted in most modern writing, including academic and business contexts. Some traditional style guides still discourage them in formal documents.

• Don't (do not). The reviewers don't usually request major revisions.
• She's (she is or she has). She's the lead author on three published papers.
• They're (they are). They're presenting their findings at the conference next week.
• It's (it is or it has). It's been two weeks since the manuscript was submitted.

Tricky Apostrophe Cases

A handful of cases come up often enough in professional writing to need their own attention. Each one trips up writers who otherwise apply the basic rules well.

Joint vs. Separate Possession

When two people own something together, add 's to the second name only. When two people own separate things, add 's to each name.

• Joint: Cesar and Maribel's home is constructed of redwood. (One home, owned by both.)
• Separate: Cesar's and Maribel's homes are both lovely. (Two homes, one belonging to each.)

Compound Nouns

For singular compound nouns, add 's at the end of the full term. For plural compound nouns, form the plural first, then add 's.

• My mother-in-law's recipe is the best in the family.
• The attorney-general's statement was released yesterday.
• My two brothers-in-law's birthdays fall in the same week.

Family Names

Family names cause some of the most common errors. The rule depends on whether you're pluralizing or showing possession.

• The Smiths means the family. The Smiths are coming for dinner.
• The Smiths' house means the house belonging to the Smith family. We went to the Smiths' house.
• The Smith's house would mean the house belonging to one person named Smith. Use only when referring to one Smith, not the whole family.
• For names ending in "s," "x," "z," "ch," or "sh," add "es" to form the plural. The Joneses, the Martinezes, the Foxes, the Sanchezes.

"For Goodness' Sake" and Similar Phrases

Some traditional phrases drop the second "s" in the possessive to avoid awkward sound repetition. The apostrophe stays.

• For goodness' sake (not "goodness's sake")
• For conscience' sake (not "conscience's sake")
• For appearance' sake (not "appearance's sake")

Common Apostrophe Mistakes

1. The Greengrocer's Apostrophe

This mistake is named for the apostrophes that often appear on produce signs. It involves adding an apostrophe to a basic plural, which is never correct. Plurals don't take apostrophes.

• Incorrect: Fresh lemon's for sale.
• Correct: Fresh lemons for sale.
• Incorrect: The Johnson's are coming for dinner.
• Correct: The Johnsons are coming for dinner.

2. Its vs. It's

Confusing "its" and "it's" is the single most common apostrophe error in English writing. The rule is simple. "It's" always means "it is" or "it has." If you can't substitute either of those phrases into the sentence, use "its" without an apostrophe. "Its" is the possessive form of "it," like his or hers, neither of which takes an apostrophe.

• Incorrect: The dog lifted it's leg.
• Correct: The dog lifted its leg. (possessive pronoun)
• Incorrect: Its going to rain tomorrow.
• Correct: It's going to rain tomorrow. (contraction of "it is")

For a complete explanation with more examples, see the article on It's vs. Its.

3. Decades and Acronyms

Don't use an apostrophe when pluralizing decades or acronyms. The apostrophe would imply possession, which isn't the meaning intended.

• Incorrect: This is popular music from the 1990's.
• Correct: This is popular music from the 1990s.
• Incorrect: I have several DVD's in my collection.
• Correct: I have several DVDs in my collection.
• Incorrect: The company hired three new CEO's last year.
• Correct: The company hired three new CEOs last year.

The exception is for plurals of single lowercase letters, where an apostrophe prevents misreading. Mind your p's and q's.

4. Possessive Pronouns Never Take Apostrophes

The possessive pronouns yours, his, hers, ours, theirs, and its never take apostrophes. This trips up many writers because most other possessives do use apostrophes.

• Incorrect: The book is your's.
• Correct: The book is yours.
• Incorrect: That decision is their's to make.
• Correct: That decision is theirs to make.

What Is a Hyphen?

A hyphen (-) is a short punctuation mark used to join words or parts of words. It's shorter than both the en dash (–) and the em dash. Its primary purpose is to connect compound terms and clarify meaning. The hyphen sits on the keyboard next to the zero on most layouts and requires no special character entry.

Hyphen vs. En Dash vs. Em Dash

These three marks look similar but have distinct uses in professional writing. Knowing which to use prevents the most common dash errors in published work.

When to Use a Hyphen

1. Compound Modifiers Before Nouns

When two or more words work together to modify a noun, hyphenate them when they appear before the noun. The hyphen tells the reader that the words function as a single unit of meaning.

• Well-known singer
• State-of-the-art laboratory
• Eight-year-old child
• Long-term investment
• Peer-reviewed journal

When the same modifiers appear after the noun, hyphens are typically not needed because the words no longer need to be linked to clarify meaning.

• The singer is well known.
• The laboratory is state of the art.
• The child is eight years old.
• The investment is long term.

2. Compound Numbers and Fractions

Hyphens are used in written-out numbers from twenty-one to ninety-nine and in fractions when they function as modifiers.

• Twenty-two students attended the seminar.
• The meeting lasted forty-six minutes.
• A two-thirds majority is required to pass the motion.
• The bottle is one-quarter full.

3. Prefixes

Most prefixes attach directly to the root word without a hyphen (preexisting, nonprofit, antibiotic). Use a hyphen with a prefix only in these specific situations.

• Before proper nouns: pre-Victorian, anti-American, post-Soviet
• With self-, ex-, and all-: self-respect, ex-partner, all-inclusive
• To avoid confusion: re-cover (to cover again) versus recover (to get better); re-sign (to sign again) versus resign (to quit)
• When the prefix ends with the same letter the root word begins with: anti-inflammatory, co-owner, de-emphasize

4. Avoiding Ambiguity

A hyphen can change the meaning of a phrase entirely. Use one when the absence of a hyphen would create confusion.

• A small-business owner is the owner of a small business.
• A small business owner could be read as a business owner who is short.
• Thirty-odd people means slightly more than thirty.
• Thirty odd people means thirty people who are strange.

5. Suspended Hyphens

When two compound modifiers share the same second element, you can use a "suspended" or "hanging" hyphen to avoid repetition. The hyphen stays attached to the first part, followed by a space.

• The class is for 9- to 13-year-olds.
• Both short- and long-term goals were discussed.
• The course covers first- and second-year material.

Common Hyphen Mistakes

1. Confusing Hyphens with En Dashes

A hyphen is not the same as an en dash. Use an en dash for ranges, connections, and relationships, not a hyphen. Most word processors will autocorrect a hyphen to an en dash when typed between numbers.

• Incorrect: The meeting will run from 1-3 p.m.
• Correct: The meeting will run from 1–3 p.m.
• Incorrect: See pages 45-67 for the full report.
• Correct: See pages 45–67 for the full report.

2. Hyphenating Adverb-Adjective Combinations

When an adverb ending in "-ly" modifies an adjective, no hyphen is needed. The "-ly" ending already signals that the adverb is modifying what comes next, so the hyphen is redundant.

• Incorrect: It was a highly-rated event.
• Correct: It was a highly rated event.
• Incorrect: She is a widely-respected scholar.
• Correct: She is a widely respected scholar.

This rule applies only to adverbs ending in "-ly." Adverbs that don't end in "-ly" (well, ill, best, little) still take hyphens in compound modifiers. A well-respected scholar. An ill-conceived plan.

3. Inconsistent Hyphenation

Be consistent with hyphenation across similar constructions within the same document. Inconsistency signals a lack of editorial care to readers and reviewers.

• Incorrect: She is a well-respected, high profile expert.
• Correct: She is a well-respected, high-profile expert.

4. Unnecessary Hyphens with Prefixes

Most common prefixes don't require hyphens. Modern usage has dropped hyphens from many compound words that historically used them.

• Incorrect: The pre-existing condition
• Correct: The preexisting condition
• Incorrect: A non-profit organization
• Correct: A nonprofit organization
• Incorrect: An e-mail address
• Correct: An email address

When in doubt, check Merriam-Webster. If the dictionary lists the closed form (preexisting, nonprofit, email) as the primary entry, use the closed form.

Memory Tricks That Always Work

A few simple tricks make these rules easier to remember.

• The apostrophe = missing letters trick.
  An apostrophe in a contraction always marks where letters have been removed. If letters can be added back ("it is" or "do not"), use the apostrophe. If nothing was removed, no apostrophe is needed.
• The possessive pronoun trick.
  Possessive pronouns in English never take apostrophes. If you wouldn't write her's, their's, or your's, don't write it's when you mean possession.
• The plural test.
  Apostrophes show possession or contractions, never simple plurals. Lemons, not lemon's. The Johnsons, not the Johnson's.
• The hyphen-before-noun rule.
  Compound modifiers get hyphenated before the noun they describe (a well-known singer), not after (the singer is well known).
• The "-ly" exception.
  Adverbs ending in "-ly" never take a hyphen before the next word. Highly rated, not highly-rated.

Quick Reference: Apostrophes and Hyphens

• Apostrophes show possession or form contractions. Never use them for simple plurals.
• "It's" always means "it is" or "it has." Use "its" for the possessive.
• Possessive pronouns (yours, his, hers, ours, theirs, its) never take apostrophes.
• Don't use apostrophes when pluralizing decades (1990s) or acronyms (DVDs, CEOs).
• Hyphenate compound modifiers before a noun, but not after.
• Don't hyphenate adverb-adjective combinations when the adverb ends in "-ly."
• Use an en dash, not a hyphen, for ranges and connections.
• Most prefixes don't require hyphens. Use hyphens only with proper nouns, self-/ex-/all-, to avoid confusion, or when the prefix and root share the same letter.
• When in doubt, consult Chicago Manual of Style, AP Stylebook, or Merriam-Webster, or work with an expert editor.

Quiz: Test Your Knowledge

Choose the correctly punctuated option in each question below.

1. Apostrophe Quiz:
   • a) The Smiths' house
   • b) The Smiths's house
   • c) The Smith's house
2. Hyphen Quiz:
   • a) She's a well known editor.
   • b) She's a well-known editor.
   • c) She's a well known-editor.
3. Apostrophe or No Apostrophe:
   • a) Its time to begin.
   • b) It's time to begin.
   • c) Its' time to begin.
4. Hyphen Applications:
   • a) A mid-century modern house
   • b) A mid century modern house
   • c) A midcentury modern house
5. Adverb-Adjective Combinations:
   • a) A highly-rated restaurant
   • b) A highly rated restaurant
   • c) A highly,rated restaurant
6. Joint Possession:
   • a) Cesar's and Maribel's home is on the corner.
   • b) Cesar and Maribel's home is on the corner.
   • c) Cesars and Maribels home is on the corner.
7. Pluralizing Decades:
   • a) Music from the 1980's was distinctive.
   • b) Music from the 1980s was distinctive.
   • c) Music from the 1980s' was distinctive.

Answers: 1-a (the family named Smith), 2-b, 3-b, 4-a (Chicago Manual of Style) or 4-c (Merriam-Webster), 5-b, 6-b (joint possession), 7-b.

Frequently Asked Questions

Is it "James's car" or "James' car"?

Both forms are correct depending on which style guide you follow. Chicago Manual of Style (17th edition) recommends adding 's to all singular nouns ending in s, including proper nouns: James's car. AP Stylebook recommends adding only an apostrophe to singular proper nouns ending in s: James' car. Most academic, book, and corporate publishing follows Chicago. Most journalism follows AP. Choose one style guide and apply it consistently throughout your document.

What's the difference between "its" and "it's"?

"It's" is a contraction of "it is" or "it has," and always takes an apostrophe. "Its" is the possessive form of "it," and never takes an apostrophe. The simplest test: if you can replace the word with "it is" or "it has" and the sentence still makes sense, use "it's." Otherwise, use "its." For example: "It's raining" works as "It is raining," so use "it's." "The dog wagged its tail" doesn't work as "The dog wagged it is tail," so use "its."

When should you hyphenate compound modifiers?

Hyphenate compound modifiers when they appear before the noun they modify, like "state-of-the-art technology," "full-time job," or "peer-reviewed journal." Don't hyphenate when the same modifiers appear after the noun: "The technology is state of the art," "The job is full time," "The journal is peer reviewed." The exception is when the compound is listed in the dictionary as permanently hyphenated, in which case the hyphen stays regardless of position.

What are the most common apostrophe mistakes?

The most common apostrophe errors are using apostrophes in basic plurals (oranges, not orange's), confusing "its" with "it's," misplacing the apostrophe in plural possessives (the Smiths' house, not the Smith's house when referring to the entire family), adding apostrophes to acronyms and decades (DVDs not DVD's, 1980s not 1980's), and adding apostrophes to possessive pronouns (yours, not your's; theirs, not their's). Each of these errors is corrected by remembering that apostrophes show possession or omission, never plurality.

Do you hyphenate "highly rated" or "widely respected"?

No. When an adverb ends in "-ly," don't hyphenate it to the adjective that follows, even when the pair appears before a noun. Write "a highly rated restaurant" or "a widely respected scholar," not "a highly-rated restaurant." The "-ly" ending already signals that the adverb is modifying the adjective, so the hyphen would be redundant. This rule applies only to adverbs ending in "-ly." Adverbs without that ending, such as "well," "ill," and "best," still take hyphens in compound modifiers: a well-known author, an ill-conceived plan, a best-selling novel.

When do prefixes need hyphens?

Most prefixes don't need hyphens. Use a hyphen with a prefix only in four specific cases. First, before proper nouns (pre-Victorian, anti-American). Second, with the prefixes self-, ex-, and all- (self-respect, ex-partner, all-inclusive). Third, to avoid confusion with another word (re-cover meaning to cover again versus recover meaning to get better). Fourth, when the prefix ends with the same letter the root word begins with (anti-inflammatory, co-owner, de-emphasize). In all other cases, attach the prefix directly to the root word with no hyphen and no space. Preexisting, nonprofit, antibiotic, postgraduate.

Can hyphens change the meaning of a sentence?

Yes. A single hyphen can change a sentence's meaning entirely. "Thirty odd people attended" suggests approximately thirty strange people. "Thirty-odd people attended" means slightly more than thirty people. "A small business owner" could describe a business owner of small physical stature. "A small-business owner" clearly means the owner of a small business. This is why professional editors pay close attention to hyphenation in compound modifiers, and why style guides treat hyphens as a clarity tool rather than an optional flourish.

What's the difference between a hyphen, an en dash, and an em dash?

A hyphen (-) is the shortest of the three and is used to join words or parts of words, such as in compound modifiers (well-known) and prefixes (self-respect). An en dash (–) is slightly longer and is used to indicate ranges and connections, such as in number ranges (pages 45–67) and date ranges (2010–2025). An em dash is the longest and marks a strong break in a sentence. Editor World's editorial style favors replacing em dashes with commas, colons, or periods for cleaner, more professional prose.

How do I show joint possession with two names?

When two people own something together, add 's to the second name only. "Cesar and Maribel's home" means they share one home. When two people own separate things, add 's to each name. "Cesar's and Maribel's homes" means each person has their own home. The placement of the apostrophe signals whether the ownership is joint or separate.

How do you make a compound noun possessive?

For singular compound nouns, add 's at the end of the full term. "My mother-in-law's recipe." "The attorney-general's statement." For plural compound nouns, form the plural first, then add 's. "My two brothers-in-law's birthdays." This rule applies whether the compound is hyphenated or open.

More Commonly Confused Words

Apostrophes and hyphens are part of a broader category of punctuation and word-choice issues that consistently trip up writers. For more on commonly confused word pairs and other punctuation rules, see the following Editor World articles.

• It's vs. Its. The most common apostrophe-related error in English writing.
• Advice vs. Advise. The noun ends in "c," the verb ends in "s." Same Latin root, different functions.
• Break vs. Brake. Two homophones with completely different meanings, often confused in writing.
• Which vs. That. Two relative pronouns that follow specific rules in formal English.
• Diagnosis vs. Diagnoses. A Greek-origin singular and plural pair that follows different rules from standard English plurals.

When to Get Help with Your Writing

Misplaced apostrophes and missing hyphens are small errors. Reviewers, instructors, and clients notice. The cumulative effect of small punctuation errors is what often turns polished writing into work that needs revision.

AI grammar checkers regularly miss these specific errors. They flag obvious misspellings but often pass over apostrophe placement issues like "the Smith's house" (referring to the family) or hyphenation issues like "a highly-rated restaurant." Some autocorrect tools introduce errors by changing its to it's automatically. A human editor catches what automated tools don't.

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This article was reviewed by the Editor World editorial team. Editor World, founded in 2010 by Patti Fisher, PhD, provides professional editing and proofreading services for students, academics, researchers, and businesses worldwide. BBB A+ accredited since 2010 with 5.0/5 Google Reviews and 5.0/5 Facebook Reviews. More than 100 million words edited for over 8,000 clients in 65+ countries.