In a Vietnamese relative clause, mà can stand between the head noun and the clause that modifies it: người mà tôi gặp “the person I met.” It marks the beginning of the modifier, but it does not mean English who, whom, or which by itself. The noun’s grammatical role is represented by a gap somewhere inside the relative clause.
Mà is often optional. người tôi gặp and người mà tôi gặp can identify the same person; the second makes the boundary more audible and is especially helpful when the noun phrase or relative is long. This page explains that linking function. The exact pattern in which the head noun is the missing subject is reserved for Subject-Gap Relative Clauses.
What mà does—and does not do
The core frame is:
head noun + mà + clause containing an understood role for that noun
Anh có số điện thoại của người mà chúng ta vừa nhắc đến không?
Do you have the phone number of the person we just mentioned?
Tôi vẫn dùng chiếc máy tính mà bố mẹ mua cho tôi khi tôi vào đại học.
I still use the computer my parents bought me when I started university.
Đó là lý do mà cuộc họp bị hoãn đến tuần sau.
That is the reason the meeting was postponed until next week.
In these examples, mà announces “a modifier of the noun begins here.” It does not occupy the missing object position after nói chuyện, mua, or a semantic role such as “reason.” Unlike English whom, it has no case form; unlike English who, it does not agree with a human antecedent.
Mà versus zero
Both options occur, but they are not interchangeable in every context. Zero linking is usually the lightest choice when the head and the gap are close. Mà is useful when a listener could initially group the words another way, when the relative contains another clause, or when a speaker deliberately highlights the description. In many short object relatives, mà can sound more deliberate or careful than zero; that tendency is not an absolute speech-versus-writing rule.
| Choice | Best fit | Typical effect |
|---|---|---|
| noun + zero + short clause | clear everyday phrase | compact, fluent, informal to neutral |
| noun + mà + clause | visible or audible boundary desired | explicit; often deliberate, but also possible in speech |
| noun + mà + long embedded clause | several possible attachments | easier processing; common in careful explanation |
| comma-delimited comment | already identified referent | parenthetical; depends on punctuation and prosody |
Tớ đã đọc bài cậu gửi tối qua rồi.
I already read the article you sent last night.
Ban tổ chức đã liên hệ với những tình nguyện viên mà trưởng nhóm đề xuất trong cuộc họp sáng nay.
The organizers contacted the volunteers whom the team leader proposed in this morning’s meeting.
The first relative is short, so zero is effortless. In the second, mà prevents tình nguyện viên trưởng nhóm from being momentarily misread as a single noun sequence and makes the clause boundary explicit.
Omitting mà is not “bad spoken Vietnamese,” and including it is not automatically formal. Register arises from the entire sentence. A legal or academic sentence may use mà to manage complexity; a friend may use it in a two-word relative for emphasis.
Do not confuse three different linkers
Vietnamese uses distinct devices for distinct clause relations. Keep this minimal contrast as a diagnostic:
| Model | Analysis |
|---|---|
| Tôi biết rằng anh ấy đến. | rằng introduces the proposition that is known. |
| người mà tôi gặp | mà introduces a clause modifying người. |
| nếu trời mưa thì ở nhà | nếu...thì organizes condition and consequence. |
| vì bận nên tôi về sớm | vì...nên organizes cause and result. |
After a speech or thought verb, conversational Vietnamese often uses là or zero rather than rằng. It does not normally substitute relative mà for English complementizer that.
Tôi nghĩ là người mà anh cần gặp đang ở tầng ba.
I think the person you need to meet is on the third floor.
The first linker, conversational là, introduces what I think. The second, mà, opens a relative modifying người. Their coexistence shows that English that corresponds to more than one Vietnamese structure.
Be equally careful with clause-final mà in conversation, as in Tôi biết mà! “I know, of course!” There it is an informal discourse particle adding insistence or reminding; it is not the relative linker discussed here.
Mà before a complex relative
The relative after mà can contain its own temporal, conditional, causal, concessive, or purpose structure. The outer linker and inner connective do different jobs.
Chúng tôi cần một phương án mà nếu ngân sách bị cắt thì vẫn triển khai được.
We need an option that can still be implemented if the budget is cut.
Cô ấy là người mà dù gặp khó khăn vẫn không bỏ cuộc.
She is someone who does not give up even when she faces difficulties.
Anh gửi giúp tôi tài liệu mà chị Hương đã chuẩn bị để khách hàng đọc trước nhé.
Please send me the document Hương prepared for the client to read in advance.
In the first example, mà marks the relative, and nếu...thì marks the condition inside it. In the second, dù...vẫn marks concession. In the third, để introduces the purpose of preparing the document. The head is still outside all those inner links.
A reported-speech clause can also sit inside a relative:
Đây là ứng viên mà giám đốc nói là có nhiều kinh nghiệm nhất.
This is the candidate whom the director said had the most experience.
Here mà starts the relative, and colloquial là starts the reported proposition. The candidate is understood as the subject of có nhiều kinh nghiệm nhất. In more formal writing, rằng can replace là, but conversational Vietnamese frequently chooses là or zero.
Dialogue: one word makes the grouping easier
A: Chị đã gọi cho nhân viên mới khách hàng khen chưa? B: Ý em là nhân viên mới mà khách hàng khen hôm qua à?
A: Have you called the new employee the client praised? B: You mean the new employee whom the client praised yesterday?
The first turn is possible in fast speech but briefly ambiguous: nhân viên mới may mean “new employee,” and the following noun khách hàng arrives without an overt boundary. B repeats the noun phrase with mà, making it unmistakable that khách hàng khen hôm qua modifies nhân viên mới. The added linker does not change who praised whom; it changes how easily the structure is recovered.
A: Sao anh chọn căn phòng ấy? B: Vì đó là phòng mà khi đến xem thì cả hai vợ chồng đều thích.
A: Why did you choose that room? B: Because it is the room that both spouses liked when they came to view it.
The answer combines outer causal vì, relative mà, and inner temporal-conditional khi...thì. In very formal prose, this many layers may be better divided into two sentences. In conversation, intonation and mà keep the intended attachment available.
Mà as relative linker versus adversative mà
The same form can link propositions with an adversative value close to “but,” especially in conversation: Tôi gọi rồi mà anh ấy không nghe máy “I called, but he did not answer.” That mà follows a complete clause and contrasts it with another. Relative mà follows a head noun and introduces a modifier containing a role for that noun.
Tôi chọn chiếc áo mà chị bảo hơi đắt, nhưng mặc lên lại rất vừa.
I chose the shirt that you said was a little expensive, but it fits very well.
The first mà is relative; nhưng explicitly marks the later contrast. Keeping the functions separate is particularly important when editing long prose.
Common Mistakes
1. Treating mà as a subject pronoun
❌ Mà đang chờ là bạn tôi.
Incorrect: mà cannot stand alone as a subject corresponding to English ‘the one who.’
✅ Người đang chờ rất sốt ruột.
The person who is waiting is very impatient.
The head noun supplies the understood subject of đang chờ; no pronoun is needed inside this short relative.
2. Copying English whom plus an object pronoun
❌ Người mà tôi mời cô ấy đã đến.
Incorrect for the ordinary reading: cô ấy fills the object position that should be a gap.
✅ Người mà tôi mời đã đến.
The person I invited has arrived.
Simple relatives normally use a gap, not both mà and a resumptive object pronoun.
3. Using mà after a verb merely because English has that
❌ Tôi biết mà anh ấy sẽ đến muộn.
Incorrect as a neutral complement: mà does not introduce the content of biết here.
✅ Tôi biết là anh ấy sẽ đến muộn.
I know that he will arrive late.
Conversational là is natural; careful writing could use rằng, and zero is also possible.
4. Losing the inner connective pair
❌ Đây là kế hoạch mà tuy tốn kém nên vẫn phải làm.
Incorrect: tuy requires a concessive continuation, not causal-result nên.
✅ Đây là kế hoạch mà tuy tốn kém nhưng vẫn phải làm.
This is a plan that, although expensive, still has to be carried out.
The outer mà marks the relative; inner tuy...nhưng marks concession. Dù...vẫn would be another coherent option.
Key Takeaways
- Relative mà marks the boundary after a head noun; it is not a relative pronoun.
- Mà and zero are both natural. Choose mà when it improves parsing, emphasis, or clarity.
- Do not use relative mà as a default translation of complementizer that.
- A relative after mà may contain rằng, là, nếu...thì, vì...nên, tuy...nhưng, dù...vẫn, để, khi, trước khi, or sau khi; each marks a separate relation.
- The missing subject pattern begins on the next page rather than being encoded by mà itself.
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Start learning Vietnamese →Related Topics
- Postnominal Relative ClausesB1 — Place a Vietnamese relative clause after its head noun and connect it to the wider system of explicit and implicit clause linking.
- Subject-Gap Relative ClausesB1 — Build Vietnamese relatives in which the head noun supplies the unspoken subject of the following predicate.
- Rằng and Declarative ComplementsA2 — Use rằng to introduce a declarative clause after verbs of saying, thinking, knowing, and believing, especially in careful or written Vietnamese.
- Zero Complementizers after Speech and ThoughtB1 — Recognize when Vietnamese naturally places a reported proposition directly after a speech or thought verb with no overt word for ‘that.’