When it comes to possessive grammar, few debates are as persistent—or as confusing—as the choice between Thomas’s or Thomas.” For writers, editors, students, and professionals alike, knowing when and how to apply the possessive apostrophe for names ending in “s” is crucial for credibility and clarity. The dilemma isn’t about which is correct universally; rather, it’s about context, style guide allegiance, and audience expectations. In this guide, we decode the rules, highlight real-world examples, and provide strategies to make confident decisions when encountering this grammatical puzzle.
Understanding the Dilemma of “Thomas’s” or “Thomas’”
The confusion around “Thomas’s car” vs. “Thomas’ car” is deeply rooted in differing grammatical conventions. Both forms indicate possession, but the disagreement stems from pronunciation, readability, and editorial preferences. Some hear the extra “s” as redundant, while others see its omission as a break in consistency.
Grammar Authorities and Their Positions
The Chicago Manual of Style (CMOS): Embracing Structure and Sound
CMOS champions consistency and pronunciation. According to this guide:
- Always add ’s, even for singular names ending in s.
- CMOS examples:
- Thomas’s schedule
- Harris’s journal
- Alexis’s ambition
This rule reflects how possessives are often pronounced in speech and is the go-to choice for academic, literary, and formal publishing.
Associated Press (AP) Style: Prioritizing Brevity and Clarity
AP Style, widely followed in journalism and broadcasting, takes a minimalist approach:
- Add only an apostrophe for singular names ending in s.
- AP examples:
- Thomas’ schedule
- Harris’ journal
- Alexis’ ambition
This convention caters to the need for quick reading and cleaner typesetting, making it ideal for news content.
Real-World Examples Across Diverse Contexts
Scenario 1: In the Kitchen with a Culinary Pro
Imagine Thomas is a celebrated chef:
- CMOS: “Thomas’s recipes revolutionized the culinary scene.”
- AP: “Thomas’ recipes revolutionized the culinary scene.”
The pronunciation in both cases remains the same, but CMOS adds a visual ‘s’ for consistency.
Scenario 2: Hospital Naming Conventions
In institutional naming, historical preferences often take precedence.
- UK Usage (AP-style): “St Thomas’ Hospital”
- Modernized (CMOS): “St Thomas’s Hospital”
Here, branding and tradition often trump stylistic rules.
Scenario 3: The Family Reunion
When describing family events, either form works depending on your style guide:
- CMOS: “Thomas’s family planned the entire reunion.”
- AP: “Thomas’ family planned the entire reunion.”
Consistency within the document matters more than which version is selected.
Scenario 4: Higher Education Branding
Institutions choose one form and stick to it for branding:
- St. Thomas University uses: “St. Thomas’ dedication to excellence.”
- CMOS would suggest: “St. Thomas’s dedication to excellence.”
Each variation reflects a strategic editorial choice, not a grammatical flaw.
Why Are We Split on This? Decoding the Discrepancy
The inconsistency exists because language is fluid. Rules evolve from usage, not the other way around. Some guides preserve tradition and sound, while others aim for simplicity and modern adaptability.
What sounds clearer? What’s easier to read? These are subjective factors that influence style guide rules. The result: both “Thomas’s” and “Thomas’” are acceptable, but they serve different audiences.
Strategic Decision-Making for Writers
To decide between the two forms, ask:
- Who is your audience?
- Are you writing for a publication that follows CMOS or AP?
- What form sounds natural aloud?
- Can you maintain that style throughout your work?
Once you’ve chosen a convention, consistency becomes more important than perfection.
Beyond Thomas: Common Possessive Puzzles
Modern Names Ending in “s”
- CMOS: James’s backpack, Harris’s notes
- AP: James’ backpack, Harris’ notes
Both reflect stylistic alignment, not grammatical errors.
Classical and Religious Figures
Here, most guides—including CMOS and AP—agree:
- Socrates’ wisdom
- Jesus’ teachings
- Moses’ laws
These exceptions stem from tradition and phonetic smoothness.
Plural Possessives That Already End in “s”
This rule is universally agreed upon:
- The teachers’ lounge
- The dogs’ toys
- The Smiths’ vacation home
The apostrophe goes after the plural “s” to avoid redundancy.
Grammar in Context: When Rules Should Bend
For informal writing like emails, blog posts, or social media, clarity beats strict adherence. Readers expect fluid, conversational tone rather than textbook precision.
But in academic or legal writing, adherence to a defined style guide matters. Choose one and follow it consistently to build professional credibility.
Helpful Tools for Getting Possessives Right
- Read Aloud – Trust your ear. If it sounds wrong, it likely is.
- Identify Your Audience – Academic, journalistic, or personal?
- Stick to One Style – Mixing styles in the same piece confuses readers.
- Reframe When in Doubt – Use phrases like “the office of Thomas” to bypass the dilemma.
Language Is Always Evolving
What we debate today might be obsolete tomorrow. As language shifts to accommodate digital brevity, the possessive apostrophe may face even more change. It’s not just grammar—it’s branding, tone, and even culture.
Modern platforms encourage simplification, so we may see broader adoption of the AP-style approach. Still, professional and academic disciplines continue to favor the structure of CMOS.
Conclusion: Choose with Confidence
Both Thomas’s and Thomas’ are grammatically valid, depending on your style guide and purpose. The true key lies in:
- Clarity
- Consistency
- Context
By understanding the logic behind each form, you gain the power to make deliberate, informed choices that elevate your writing. Trust your style guide, consider your audience, and never let grammar obstruct effective communication.
