When to Use That vs Who: A Quick Guide to Correct Grammar
Choosing between that and who in everyday writing feels minor, yet it shapes how readers judge clarity and tone.
The distinction rests on grammar rules, not style whims, and mastering it sharpens both professional and casual prose.
Core Rule: Restrictive vs. Non-Restrictive Clauses
A restrictive clause narrows the meaning of its noun and is essential to the sentence’s core message.
Non-restrictive clauses add extra, removable information and are set off by commas.
These two clause types decide whether that or who is grammatically correct.
Restrictive Clause Examples
The author that signed your book is waiting outside.
Without the clause, we do not know which author is meant.
Using who here would be considered informal by many editors.
Non-Restrictive Clause Examples
J.K. Rowling, who wrote the Harry Potter series, is speaking tonight.
The main point remains intact if the clause is removed.
Replacing who with that in this construction jars standard usage.
People vs. Things: The Traditional Distinction
Traditional grammar insists on who for people and that for animals or objects.
This rule still guides formal academic and journalistic writing.
However, relaxed registers increasingly accept that for people, especially in spoken English.
When to Honor the Rule
Use who when addressing a person’s identity or role in formal contexts.
Example: The senator who drafted the bill will vote today.
Substituting that here can sound dismissive or robotic.
When to Bend the Rule
Marketing copy and dialogue may use that for people to create a conversational feel.
Example: The candidate that connects with voters wins.
Recognize the trade-off: warmth versus grammatical precision.
Punctuation Signals: Commas and Their Impact
Commas act as traffic lights for relative pronouns.
Their presence or absence immediately signals which pronoun is appropriate.
Train your eye to scan for commas before deciding on that or who.
Comma Present
If you see a comma before the clause, default to who for people.
Example: Dr. Morales, who pioneered the vaccine, is retiring.
The comma guarantees non-restrictive status.
Comma Absent
No comma suggests a restrictive clause, opening the door to that or who depending on register.
Example: The scientist that solved the equation is only 28.
Removing the clause would leave the sentence vague.
Style Guides at a Glance
Each major manual treats the that/who question with slight nuance.
Knowing these preferences prevents needless edits.
Chicago Manual of Style
Chicago prefers who for people in all restrictive clauses, deeming that for people as “acceptable but less polished.”
Example revision: Replace “the lawyer that argued” with “the lawyer who argued.”
AP Stylebook
AP allows that for people in tight journalistic space but still favors who in features.
The distinction preserves readability under column-inch pressure.
APA Publication Manual
APA sides with Chicago, reserving who for humans and that for non-humans.
This choice aligns with scholarly precision.
Common Pitfalls and Quick Fixes
Writers often swap the pronouns when rushing or when influenced by speech patterns.
Spotting these errors early saves revision time.
Pitfall: “The person that called”
Quick fix: Change to “the person who called” in formal documents.
Retain that only if mirroring direct speech.
Pitfall: Overcorrecting to “The company who”
Organizations and brands are not people; use that.
Exception: personified brands in creative marketing may earn who for effect.
Subtle Tone Shifts
Who humanizes.
That objectifies.
The choice can alter reader empathy in a single clause.
Legal Writing Example
The plaintiff who suffered damages sounds more sympathetic than the plaintiff that suffered damages.
Court briefs benefit from this nuance.
Tech Documentation Example
The server that crashed at midnight avoids anthropomorphism and stays precise.
Using who here would confuse readers.
Relative Pronouns in Questions
Interrogative structures follow the same logic.
“Who” becomes the interrogative pronoun, while the relative clause inside the question still decides that vs. who.
Embedded Clause Example
Do you know the manager who approved the budget?
Here, the relative clause remains restrictive, so who fits.
Indirect Question Example
She asked which candidate that the committee had selected.
The relative pronoun must still agree with the noun it modifies, even inside an indirect question.
Editing Checklist for Writers
Print your draft and circle every relative pronoun.
Ask two questions: Is the noun human? Is the clause restrictive?
Apply the flowchart: human + restrictive → who; human + non-restrictive → who with commas; non-human + restrictive → that; non-human + non-restrictive → which with commas.
Advanced Considerations: Animacy and Euphony
Linguists note that animacy—how alive something feels—sometimes overrides the human rule.
Pets, beloved cars, or cherished robots may earn who in creative contexts.
Euphony also plays a role; who can break a string of that clauses to avoid monotony.
Creative Fiction Sample
The starship who dreamed of stars was more than steel and code.
Here, personification justifies the pronoun choice.
Corporate Branding Sample
Meet Toyota who never lets you down—an intentional humanizing tactic in advertising.
Copywriters weigh the emotional payoff against grammatical risk.
Non-Standard Dialects and Usage Evolution
Some dialects treat that as a universal relative pronoun.
Academic writing must still adhere to standard norms, but dialogue can mirror authentic speech.
Understanding the sociolinguistic backdrop prevents blanket “corrections” that erase voice.
Practical Exercise: Rewrite for Precision
Take the sentence: “The engineer that designed the bridge won an award.”
Formal revision: “The engineer who designed the bridge won an award.”
Conversational revision remains unchanged if mimicking spoken tone.
SEO Implications for Content Creators
Search engines do not rank pages on that versus who alone.
Yet consistent grammar increases dwell time and reduces bounce rate, indirect SEO signals.
Clear relative clauses also improve voice-search parsing.
Schema Markup Example
When marking up FAQ content, use who for person entities in JSON-LD strings to align with Google’s preferred natural language.
Example: “acceptedAnswer”: “The author who wrote the guide is Jane Lee.”
Memory Aids for Quick Recall
Think “Humans who, things that.”
Picture a comma as a gentle pause that waves in who.
These two mnemonics cover 90 percent of cases.
Final Professional Tip
Set your spell-checker to flag every that introducing a human noun.
Review each instance for register and tone, then lock in your choice.