Simple explanation
What is a reduced relative clause? A reduced relative clause is a shorter form of a relative clause. Instead of saying The woman who is waiting outside is my manager, you can often say The woman waiting outside is my manager. The reduced version removes words that are grammatically unnecessary while keeping the main relationship between the noun and the description clear. The first decision: active or passive? Before reducing a relative clause, identify the relationship between the noun and the verb. If the noun performs the action, the meaning is active and an -ing form is often used. If the noun receives the action, the meaning is passive and a past participle is usually used. This active-passive distinction is the most important principle in this grammar point. Reducing active relative clauses with -ing When the noun performs the action in the relative clause, the clause can often be reduced to an -ing phrase. The students who are waiting outside becomes The students waiting outside. This is also possible with general or repeated situations, not only actions happening right now. People who work from home can become People working from home. Reducing passive relative clauses with a past participle When the noun receives the action, the relative pronoun and the appropriate form of be can often be removed, leaving the past participle. The documents that were sent yesterday becomes The documents sent yesterday. This pattern is especially common in formal, academic and professional English. Reducing clauses with be, adjectives and prepositional phrases If a relative clause contains who, which or that followed by be and then an adjective or prepositional phrase, the relative pronoun and be can often be omitted. People who are interested in the course becomes People interested in the course. The files that are on the desk becomes The files on the desk. Using the to-infinitive After expressions such as the first, the second, the last, the next and the only, a relative clause can often be reduced to a to-infinitive. She was the first person who noticed the mistake becomes She was the first person to notice the mistake. This structure is particularly common in formal English. Reduction is different from simply omitting a relative pronoun Not every sentence without who, which or that contains a reduced relative clause. In The book that I bought yesterday, that is the object of bought and can simply be omitted: The book I bought yesterday. The verb itself does not change. By contrast, The man who is standing outside becomes The man standing outside, so the clause structure is genuinely reduced. When should a relative clause not be reduced? Do not reduce a relative clause if the reduction removes important information about time, possibility, obligation or another modal meaning. For example, Employees who will work on the new project clearly refers to future workers. Employees working on the new project may suggest that they already work on it. If the meaning becomes less precise, keep the full relative clause.
Grammar formula
Active relative clause
noun + who/which/that + active verb → noun + verb-ingThe people who work here → The people working here
Active progressive relative clause
noun + who/which/that + be + verb-ing → noun + verb-ingThe woman who is talking to Ben → The woman talking to Ben
Passive relative clause
noun + who/which/that + be + past participle → noun + past participleThe letters that were sent yesterday → The letters sent yesterday
Adjective phrase
noun + who/which/that + be + adjective → noun + adjectivePeople who are interested → People interested
Prepositional phrase
noun + who/which/that + be + prepositional phrase → noun + prepositional phraseThe books that are on the table → The books on the table
To-infinitive reduction
the first/last/only/next + noun + relative clause → the first/last/only/next + noun + to + verbThe first person who arrived → The first person to arrive
Core rules
- 1
Use -ing for active meaning
If the noun performs the action, reduce the relative clause with an -ing form where appropriate. People who live nearby becomes People living nearby.
- 2
Use a past participle for passive meaning
If the action is done to the noun, use the past participle. Products that are made locally becomes Products made locally.
- 3
Remove relative pronoun plus be before certain descriptions
Who, which or that plus be can often be omitted before an adjective, participle or prepositional phrase. Anyone who is interested becomes Anyone interested.
- 4
Use a to-infinitive after certain limiting expressions
After expressions such as the first, the last, the next and the only, a relative clause can often be reduced with to plus the base verb.
- 5
Keep the noun-participle relationship clear
The reduced phrase must clearly describe the noun immediately before it. If the relationship is ambiguous, use a full relative clause instead.
- 6
Do not remove essential tense or modal meaning
A reduction should not erase important information about future time, obligation, possibility, intention or another meaning carried by the original clause.
Useful examples
The woman waiting outside is our new manager.
The woman who is outside and waiting is our new manager.
waiting outside is the reduced form of who is waiting outside.
Students living away from home often become more independent.
Students who live away from home often learn to be more independent.
The -ing form can describe a general situation, not only something happening now.
The man wearing the black coat is my neighbor.
The man who has the black coat on is my neighbor.
wearing reduces who is wearing.
Anyone wanting more information can contact us by email.
Anyone who wants additional information can email us.
wanting has active meaning because anyone is the person who wants the information.
The documents sent yesterday have already arrived.
The documents that were sent yesterday have already reached their destination.
sent is a past participle with passive meaning.
The products made in this factory are exported worldwide.
The products that this factory produces are exported around the world.
made is passive because the products receive the action.
The data collected during the experiment will be analyzed next week.
The data gathered during the experiment will be examined next week.
collected reduces a passive relative clause.
The people injured in the accident were taken to hospital.
The people who were hurt in the accident were taken to hospital.
injured describes people affected by the event.
The books on the top shelf belong to my professor.
The books that are located on the highest shelf belong to my professor.
on the top shelf reduces that are on the top shelf.
Employees responsible for customer complaints should attend the meeting.
Employees who handle responsibility for customer complaints should attend the meeting.
responsible for customer complaints reduces who are responsible for customer complaints.
She was the first person to notice the mistake.
She was the person who noticed the mistake before everyone else.
The to-infinitive is natural after the first person.
He was the only candidate to answer every question correctly.
He was the one candidate who got every answer right.
The to-infinitive commonly follows the only plus a noun.
Passengers traveling with small children may board first.
Passengers who are traveling with young children may enter the aircraft first.
traveling has active meaning because passengers perform the action.
The apartment advertised online looked much larger in the photos.
The apartment that was promoted online appeared much bigger in the pictures.
advertised has passive meaning because the apartment was advertised.
Common mistakes
- ❌ The people wait outside are my colleagues. ✅ The people waiting outside are my colleagues. A reduced active relative clause normally requires the -ing form, not the base form of the verb.
- ❌ The report writing by Emma was very detailed. ✅ The report written by Emma was very detailed. The report does not perform the action of writing. It receives the action, so the past participle written is required.
- ❌ The students studied in the library are from my course. ✅ The students studying in the library are from my course. If the students are the people doing the studying, the relationship is active, so studying is needed.
- ❌ The woman who talking to the receptionist is my teacher. ✅ The woman talking to the receptionist is my teacher. You cannot normally keep who directly before an -ing participle in this reduced structure. Use either who is talking or talking.
- ❌ The machines using in the factory are very old. ✅ The machines used in the factory are very old. The machines are used by people; they do not perform the action themselves. A past participle is therefore required.
- ❌ He was the first person arriving at the office. ✅ He was the first person to arrive at the office. After the first person, the to-infinitive is the standard reduced structure for this meaning.
- ❌ The book I bought it yesterday was expensive. ✅ The book I bought yesterday was expensive. In the full relative clause, that would be the object of bought. Once it is omitted, an additional object pronoun such as it must not be added.
Learning tips
- First ask whether the noun performs the action or receives it.
- Use -ing for many active reductions and a past participle for many passive reductions.
- Do not assume that an -ing form always refers to an action happening at this exact moment.
- Look for common academic patterns such as data collected, methods used, participants selected and results obtained.
- After the first, the last, the next and the only, a to-infinitive is often the most natural choice.
- Do not reduce a clause if doing so removes an important future, modal or time meaning.
- A full relative clause is often better than a reduced one if the shorter version sounds ambiguous or difficult to process.
Practise this topic
Interactive exercises for this topic are coming soon.
PlannedRelated grammar
Related dictionary words
Frequently asked questions
Can every relative clause be reduced?
No. Reduction is appropriate only when the grammatical relationship remains clear and no important information about time, modality or meaning is lost.
How do I know whether to use -ing or a past participle?
If the noun performs the action, use an -ing form in many cases. If the noun receives the action, a past participle is usually required.
Does -ing in a reduced relative clause always mean the action is happening now?
No. The -ing form can also describe a general, repeated or long-term situation, as in people working from home.
Can I always remove who, which or that?
No. Sometimes the verb form must also change. The man who is waiting becomes The man waiting, not The man wait. In other cases, an object relative pronoun can simply be omitted without changing the verb.
Why do we say the first person to arrive rather than the first person arriving?
After expressions such as the first, the last, the next and the only, English normally uses a to-infinitive for this type of reduced relative meaning.
Are reduced relative clauses mainly formal?
They occur in both spoken and written English, but they are especially common in formal, academic and informational writing because they make descriptions more compact.