Both Parties vs. Party's: How to Use Plurals and Possessives Correctly

You’ve probably stared at a screen, cursor blinking, wondering if you should type both parties is the correct plural form used when referring to two distinct groups or individuals involved in an agreement or situation or party’s. It’s a classic trap. One looks like a plural; the other screams possession with that sneaky apostrophe. Getting it wrong can make a legal document look sloppy or an email sound unprofessional.

The short answer? If you are talking about two sides in a deal, a contract, or an argument, you almost certainly want both parties. If you are talking about something belonging to one single group or individual, you might use party’s. But let’s break down exactly why, because English punctuation is full of these tiny landmines.

The Rule of Thumb: Plural vs. Possessive

To nail this down, you need to separate two different grammatical jobs: making things plural (more than one) and showing ownership (belonging to).

Plural nouns are words that indicate more than one person, place, thing, or idea, typically formed by adding 's' or 'es' without an apostrophe rarely use apostrophes. You have two cats. Three dogs. Five parties. When you add the word "both" to the mix, you are explicitly stating there are two entities. So, both parties means "the two groups." No apostrophe needed. Adding one creates parties', which is the plural possessive (belonging to multiple parties), or party's, which is singular possessive (belonging to one party). Neither fits the phrase "both..."

Think of it this way: "Both" already tells you there are two. You don’t need an apostrophe to show quantity. You just need the 's' for the plural.

• Correct: Both parties signed the contract.
• Incorrect: Both party's signed the contract.
• Incorrect: Both parties' signed the contract.

When Do You Actually Use "Party's"?

Singular possessive is a grammatical form indicating ownership or association by a single entity, marked by an apostrophe followed by s ('s) comes into play when one specific party owns something or has a characteristic. Here, the apostrophe does the heavy lifting.

If you are writing about a political campaign, a social gathering, or a legal side, and you want to say something belongs to that single unit, you use party's.

• Example: The Democratic party's platform focuses on healthcare.
• Example: We need to check the party's arrival time.

Notice the difference? In the first example, we aren't saying "both." We are talking about one party and its platform. The platform belongs to the party. Hence, the apostrophe.

The Tricky Middle Ground: "Parties'"

There is a third option that often causes confusion: parties'. This is the Plural possessive is a grammatical form indicating ownership or association by multiple entities, marked by an apostrophe after the final s of a plural noun. You use this when multiple parties share something.

This is where context matters immensely. If you are drafting a lease agreement and you want to refer to the responsibilities shared by all tenants, you might write:

All parties' obligations must be met by Friday.

However, even here, many style guides prefer rephrasing to avoid the awkward double-apostrophe look. Instead of "parties' obligations," you could write "obligations of both parties." It’s clearer and less prone to error.

Common Scenarios Where People Mess Up

Let’s look at real-world situations where this mistake happens most frequently.

1. Legal Contracts

In law, precision is everything. A contract usually defines "Parties" as the people signing it. If you write "Both party's agree to terms," a lawyer will cringe. It implies that "agree" belongs to the party, rather than being the action performed by the two parties. Always use both parties when referring to the signatories collectively.

2. Political News

Journalists often juggle multiple political groups. If you are reporting on a debate between Republicans and Democrats, you are discussing both parties. If you are discussing the internal strategy of just the Republican group, you are discussing the Republican party's strategy.

3. Social Events

You’re planning a wedding. You have the bride’s family and the groom’s family. These are both parties. You wouldn’t say "both party's families." That’s redundant and grammatically incorrect. You might say "the bride's family" (singular possessive) or "both families" (plural).

Why Does This Matter?

You might think, "It’s just a typo. Who cares?" In casual texting, nobody cares. But in professional writing, small errors signal larger carelessness. If you mess up basic punctuation in a cover letter, a client proposal, or a legal notice, the reader subconsciously questions your attention to detail elsewhere.

Moreover, ambiguity can lead to misunderstandings. In a complex sentence, mistaking a plural for a possessive can change who is responsible for what. For instance, "The party's decision" (one group made a choice) versus "The parties decided" (two groups made choices). Clear communication protects you from liability and confusion.

How to Test Yourself Instantly

Here is a simple trick I use when I’m stuck. Try replacing the word "party" with a simpler word like "person" or "group."

If you are trying to decide between both parties and both party's:

1. Replace "party" with "person."
2. Ask yourself: Would I say "both persons" or "both person's"?
3. You would definitely say "both persons" (or better yet, "both people").
4. Therefore, you should say "both parties."

Does "both person's" make sense? No. The apostrophe doesn't belong there. This substitution test works for almost any tricky plural/possessive dilemma.

Other Common Apostrophe Pitfalls

If you are struggling with parties vs. party's, you might also be tripping over these common errors:

• Its vs. It's: "Its" is possessive (the dog wagged its tail). "It's" is a contraction for "it is" (it's raining). Never put an apostrophe in "its" unless you mean "it is."
• Your vs. You're: "Your" shows ownership (your car). "You're" means "you are" (you're welcome).
• Who's vs. Whose: "Who's" means "who is" (who's there?). "Whose" shows ownership (whose book is this?).

The pattern is consistent: if you can replace the word with "is" or "are," you need the apostrophe. If you are showing ownership or making a plural, you usually don’t.

Tools to Help You Check

We all make mistakes. Even professional editors catch themselves using "party's" when they meant "parties." To stay safe, use tools.

Grammar checkers are software tools that analyze text for grammatical errors, spelling mistakes, and stylistic issues, such as Grammarly, Hemingway Editor, or Microsoft Editor like Grammarly or built-in spellcheckers in Word and Google Docs will flag incorrect apostrophe usage. They aren’t perfect-they sometimes miss context-but they catch the obvious stuff. Always read your work aloud before sending it. Your ear will often hear the clunkiness of "both party's" even if your eyes skip over it.

Summary: The Final Verdict

So, back to your original question: Is it both parties or party's?

If you are referring to two sides in any context-legal, political, social-it is both parties. Period. Save the apostrophe for when one single party owns something (the party's logo) or when multiple parties share ownership (the parties' joint account). Keep it simple. Remove the apostrophe when counting. Add it only when claiming ownership.