Reduced Relative Clauses

Overview

A relative clause can often be shortened without any loss of meaning. The result is a reduced relative clause: a compact modifier that retains the descriptive function of the full clause while removing the relative pronoun and any auxiliary verb that accompanied it. What remains is typically a participle phrase, an infinitive phrase, or a prepositional phrase that sits directly beside the noun it modifies.

Reduced relative clauses appear frequently in formal written English, particularly in academic, journalistic, and professional prose. They make sentences more concise without making them less precise. A full relative clause such as the report that was submitted on Friday can become the report submitted on Friday, which carries the same meaning in three fewer words.

The challenge is knowing when reduction is permitted and what form it takes. Not every relative clause can be reduced. Active clauses reduce differently from passive ones, and the reduced form must accurately preserve the original meaning. A misapplied reduction changes the meaning or produces an ambiguous or ungrammatical sentence.

When a Relative Clause Can Be Reduced

A relative clause can be reduced only when it is a defining relative clause and only when the relative pronoun is the subject of the clause. Non-defining relative clauses and clauses where the relative pronoun is the object cannot normally be reduced in the same way.

The relative pronoun and the verb form that follows it determine what reduction is possible. When the clause contains a progressive form (who is working, which is being processed), the pronoun and the auxiliary be are removed, leaving the present participle. When the clause contains a passive form (which was approved, that had been submitted), the pronoun and be are removed, leaving the past participle. When the clause contains a simple active verb (who works, that contains), the pronoun is removed and the verb shifts to the present participle.

In the first pair, who is is removed and the present participle reviewing remains. In the second, that was is removed and the past participle submitted remains. In the third, who is removed and wants becomes wanting.

Active Reductions: Present Participle Phrases

When the full relative clause uses an active verb, the reduced form uses a present participle. This applies to progressive clauses and to simple active clauses alike. The present participle phrase sits immediately after the noun and carries the same identifying force as the full clause.

The present participle form signals an active relationship: the noun is performing or doing something. This is the key distinction from passive reductions.

Passive Reductions: Past Participle Phrases

When the full relative clause uses a passive verb, the reduced form uses a past participle. The past participle phrase directly follows the noun and indicates that the noun is the receiver of an action rather than its performer. Both simple passive and perfect passive constructions can be reduced in this way.

Past participle reductions are particularly common in formal writing because they produce compact noun phrases that read efficiently. The findings reported in Table 3 is more economical than the findings that were reported in Table 3, and both communicate the same information with equal precision.

Reductions Using Infinitive Phrases

A relative clause can also be reduced to an infinitive phrase in specific contexts. This form typically follows superlatives, ordinals such as first, second, and last, and pronouns such as the only one and the next. The infinitive form carries a sense of sequence, possibility, or purpose that the participle form does not.

The infinitive reduction is distinct from the participial reduction in both form and implication. The last report submitted suggests a report that was submitted; the last report to be submitted implies it was the final one in a sequence.

Reductions Using Prepositional Phrases

When the full relative clause uses the verb be followed by a prepositional phrase or a noun phrase as a complement, the clause can be reduced by removing the relative pronoun and the form of be, leaving just the complement.

This type of reduction produces a clean, noun-phrase-like modifier that reads naturally in most registers, from informal to academic.

When Reduction Is Not Permitted

Not every relative clause can be reduced. Non-defining relative clauses, which are set off by commas and add supplementary information, cannot normally be reduced without a significant change to the sentence structure or register. Clauses in which the relative pronoun is the object rather than the subject also resist standard reduction.

In the first sentence, a reduced version with commas is sometimes seen in formal and journalistic prose but is not standard in all contexts and can be ambiguous. The full clause is the safer choice. In the second, that is the object of hired, not the subject, so standard participle reduction is not available.

Clauses that express a state rather than an action can also be difficult to reduce cleanly. The policy that applies to all staff reduces to the policy applying to all staff, which is natural. The system that exists to support users reducing to the system existing to support users sounds awkward, and in such cases keeping the full clause is a better editorial decision.

Defining vs. Non-Defining in Reduced Forms

Common Mistakes to Avoid

Reducing a Non-Defining Clause Without Awareness of the Change

Removing the commas and the relative pronoun from a non-defining clause converts it to a defining clause, which changes the meaning.

The defining version implies there are multiple directors and identifies which one. The non-defining version refers to one specific director and adds information about them. These are different sentences with different meanings.

Confusing Active and Passive Reductions

Using a present participle when the noun is the receiver of the action, or a past participle when the noun is the performer, reverses the intended relationship.

Leaving a Dangling Participial Phrase

A reduced relative clause must clearly modify the noun it follows. When the participial phrase appears too far from its noun, or when the sentence is restructured so that the phrase seems to modify a different noun, a dangling modifier results.

Reducing a Clause Where the Pronoun Is the Object

When the relative pronoun functions as the object of the verb inside the clause, standard participial reduction is not available.

That is the object of selected in the full clause. Selecting implies the candidate is doing the selecting, which reverses the meaning.

Producing an Ambiguous Reduced Clause

Some reductions are grammatically possible but produce ambiguity because the participial phrase could logically apply to more than one noun.

Without the full clause, it is unclear whether the manager or the analyst is reviewing the report.

Practice Exercises

Exercise 1: Reduce the Relative Clause

Rewrite each sentence by reducing the underlined relative clause to a participial or infinitive phrase.

1. The documents that were recovered from the archive date back to 1945.
2. The engineer who is leading the project has requested additional resources.
3. She was the first researcher who identified the link between the two variables.
4. All staff members who are based in the regional offices must complete the survey.
5. The policy that was introduced in January has already been amended twice.

Exercise 2: Identify the Reduction Type

Label each reduced relative clause as present participle (PP), past participle (PaP), infinitive (Inf), or prepositional phrase (Prep).

1. The analyst presenting the findings graduated last year.
2. The only candidate to withdraw from the process did so on health grounds.
3. All items stored in the facility must be labelled.
4. The delegates in the second breakout group reported the most progress.
5. Anyone working remotely must use the secure network.

Exercise 3: Correct the Error

Each sentence contains an error in the formation or placement of a reduced relative clause. Rewrite each sentence correctly.

1. The report writing by the consultant was submitted ahead of schedule.
2. Reviewed by the panel, the judges awarded the project first place.
3. She was the only applicant completing all three stages of the process.
4. The files locating in the cabinet need to be transferred to the archive.
5. The system breaking down repeatedly caused significant delays.

Summary

The key is selecting the correct participle form, placing the reduced clause immediately beside its noun, and recognising the situations where a full relative clause is the more accurate and safer choice.