Relative Clauses & Embedded Phrases — I can use relative...

SECTION 1

Historical Context & Motivation

The capacity to embed one clause inside another is among the most powerful features of human language, and our awareness of how this mechanism works has evolved over millennia. Ancient Greek and Latin grammarians were the first to classify sentence components systematically, noting that certain words—what we now call relative pronouns—served to link a subordinate description back to a noun in the main clause. The Roman rhetorical tradition valued the ability to layer information within a single periodic sentence, considering it a hallmark of educated discourse. This tradition carried forward through medieval grammar instruction and eventually shaped the formal study of English syntax that informs how we teach writing today.

~100 BCE

Latin Grammar Codified

Roman grammarians such as Varro catalogued relative pronouns (qui, quae, quod) and described how subordinate clauses modify nouns, establishing terminology still used in linguistics.

1762

Lowth's Prescriptive Grammar

Bishop Robert Lowth published A Short Introduction to English Grammar, formalizing rules about 'who' versus 'whom' and restrictive versus non-restrictive clauses that persist in style guides today.

1957

Chomsky's Generative Grammar

Noam Chomsky's Syntactic Structures demonstrated that recursion—the embedding of phrases within phrases—is a core property of human language, providing a theoretical framework for understanding relative clauses as instances of recursive structure.

1985

Functional Approaches

Linguists such as Talmy Givón and Sandra Thompson shifted focus from abstract tree diagrams to how embedded clauses function in real discourse—foregrounding information, adding background detail, or guiding reader attention—connecting syntax to rhetoric.

2000s

Corpus Linguistics & Writing Pedagogy

Large-scale corpus studies confirmed that skilled academic writers use relative clauses and embedded phrases at significantly higher rates than novice writers, prompting modern composition curricula to teach these structures explicitly as tools for precision.

The central question this lesson addresses is both ancient and urgently practical: How can a writer pack more precise, relevant detail into a sentence without losing clarity or creating awkward run-ons? Relative clauses and embedded phrases are the primary syntactic tools for achieving this balance, and understanding their structure will give you conscious control over a skill that distinguishes polished academic prose from loosely connected simple sentences.

SECTION 2

Core Principles & Definitions

Before we examine the mechanics of embedding, it is essential to establish a shared vocabulary. A clause is any grammatical unit that contains a subject and a finite verb. An independent clause can stand alone as a sentence, whereas a dependent (or subordinate) clause cannot; it relies on an independent clause for its full meaning. Relative clauses are a specific type of dependent clause introduced by a relative pronoun (who, whom, whose, which, that) or a relative adverb (where, when, why), and they function as adjectives—modifying a noun or pronoun in the main clause. Embedded phrases operate similarly but without a subject-verb pair; they include participial phrases, appositive phrases, and prepositional phrases that are inserted into the middle or end of a clause to add detail.

Restrictive vs. Non-Restrictive

A restrictive relative clause is essential to identifying the noun (no commas): "Students who submit late lose points." A non-restrictive clause adds extra information (set off by commas): "Dr. Lee, who teaches linguistics, published a new paper."

Relative Pronouns & Adverbs

The relative pronoun anchors the clause to its antecedent. Use who/whom/whose for people, which for things (non-restrictive), and that for things (restrictive). Relative adverbs where, when, why replace preposition + which.

Participial Phrases

A participial phrase uses a present participle (-ing) or past participle (-ed/-en) to modify a noun: "The researcher, analyzing the data carefully, found an anomaly." These phrases are essentially reduced relative clauses.

Appositive Phrases

An appositive is a noun phrase placed beside another noun to rename or define it: "Chomsky, a pioneering linguist, changed the field." It performs the same function as a non-restrictive relative clause with the copula removed.

The Embedding Principle

All of these structures follow a single principle: interrupt the main clause at the point of the noun being modified, insert the detail, then resume. The reader's working memory holds the main clause in suspension while processing the embedded information, then snaps back to the main predicate.

✦ KEY TAKEAWAY

Think of a relative clause or embedded phrase as a hyperlink in a web page. The main sentence is the page's primary content, and the embedded structure is the pop-up tooltip that gives the reader additional, precisely targeted information exactly where it is needed—without forcing a detour to a separate page (i.e., a separate sentence). Just as a well-placed hyperlink enriches a webpage without disrupting the reading flow, a well-placed relative clause enriches a sentence without breaking its momentum.

SECTION 3

Visual Explanation — Sentence Architecture

The following diagram illustrates how a relative clause is embedded within a main clause. The sentence under analysis is: "The professor who published the landmark study received the award." Notice how the main clause is split around the relative clause, which attaches directly to the noun it modifies.

The diagram shows how the main clause "The professor … received the award" is interrupted by the relative clause "who published the landmark study," which attaches to the noun professor. The lower comparison illustrates the difference in clarity between two separate sentences and one embedded sentence.

Observe that the relative pronoun "who" performs double duty: it simultaneously serves as the subject of the relative clause's verb published and links the entire clause back to professor in the main clause. This dual function is what makes relative pronouns uniquely efficient: a single word creates a syntactic bridge between two propositions, allowing the writer to convey both pieces of information in a single, cohesive sentence. The reader processes the embedded detail as a kind of parenthetical zoom-in on the noun, then smoothly returns to the main clause's predicate.

SECTION 4

How Embedding Works — The Mechanics of Insertion

Understanding the mechanics of embedding requires seeing it as a three-step transformation. You begin with two independent propositions, identify the shared noun between them, and then fold one proposition into the other using the appropriate connector. This section formalizes that process and extends it to embedded phrases that lack a finite verb.

Step-by-Step Embedding Algorithm

Identify the shared referent. Find the noun (or noun phrase) that appears in both the host sentence and the sentence to be embedded. Example: "The policy failed. The policy was enacted in 2019." Shared referent: the policy.
Replace the shared noun in the subordinate sentence with a relative pronoun. "The policy was enacted in 2019" → "which was enacted in 2019." Choose which or that based on whether the clause is restrictive or non-restrictive.
Insert the relative clause immediately after the noun it modifies. "The policy which was enacted in 2019 failed." If the clause is non-restrictive, set it off with commas.
Optionally reduce to a phrase. If the relative clause contains a be-verb or a single active participle, you may delete the relative pronoun and auxiliary to produce a participial or adjectival phrase: "The policy enacted in 2019 failed."

Types of Embedded Phrases (Reduced Clauses)

Common embedded phrase types and their derivation from full relative clauses

Phrase Type	Formed From	Example
Participial (present)	who/which + is/are + V-ing → V-ing	The student studying abroad sent an update.
Participial (past)	who/which + was/were + V-ed → V-ed	The data collected over five years confirmed the hypothesis.
Appositive	who/which + is/are + NP → NP	Darwin, a naturalist of extraordinary patience, spent decades refining his theory.
Prepositional	which + is/are + PP → PP	The office on the third floor handles financial aid.
Adjective phrase	who/which + is/are + Adj → Adj	The results, consistent with earlier findings, were published last month.

📝 Punctuation Rule of Thumb

If you can remove the embedded element without changing which noun is meant, it is non-restrictive and requires commas. If removing it makes the noun vague or changes the sentence's truth value, it is restrictive and takes no commas. In formal American English, use "that" for restrictive clauses and "which" (with commas) for non-restrictive clauses.

SECTION 5

Detailed Classification — A Taxonomy of Relative Clauses

Relative clauses vary not only in their restrictiveness but also in the grammatical role the relative pronoun plays within the embedded clause and in the position of the clause relative to the matrix sentence. This section provides a comprehensive taxonomy, illustrated by a visual chart, so you can recognize and deploy each type with confidence.

This taxonomy chart divides relative clauses into restrictive and non-restrictive types, further subdivided by the grammatical role of the relative pronoun (subject, object, possessive). The bottom row shows how full clauses can be reduced to embedded phrases—participial, appositive, and adjectival—for greater concision.

The chart reveals an important insight: every embedded phrase you encounter in academic writing can be traced back to an underlying full relative clause. When you see "the results obtained from the survey", the full clause would be "the results that were obtained from the survey." Recognizing this derivational relationship allows you to move fluidly between full clauses and reduced phrases depending on the rhetorical context. Use the full clause when you need maximum explicitness—for instance, when the participial form might create ambiguity about the agent—and use the reduced phrase when brevity and pace are more important.

SECTION 6

Worked Example — Building a Complex Sentence

Let us work through the process of transforming a series of simple, choppy sentences into a single sophisticated sentence using multiple embedded structures. Our starting material consists of four short sentences drawn from a hypothetical research context.

📄 Original Sentences

(1) Dr. Patel conducted a longitudinal study. (2) She is a cognitive psychologist at Stanford. (3) The study tracked 500 participants. (4) The participants had experienced childhood trauma.

Combining with Relative Clauses & Embedded Phrases

Step 1 — Identify the shared referentsSentences (1) and (2) share the referent Dr. Patel / She. Sentences (1) and (3) share the study. Sentences (3) and (4) share the participants. These overlaps tell us where embedding can occur.

Step 2 — Embed sentence (2) as an appositive modifying Dr. PatelSentence (2) renames Dr. Patel, so it becomes a non-restrictive appositive: "Dr. Patel, a cognitive psychologist at Stanford, conducted a longitudinal study." We deleted who is to reduce the clause to a phrase.

Dr. Patel, a cognitive psychologist at Stanford, conducted a longitudinal study.

Step 3 — Embed sentence (3) as a relative clause modifying 'study'Sentence (3) provides essential information about the study, so we use a restrictive relative clause with that: "…a longitudinal study that tracked 500 participants."

…a longitudinal study that tracked 500 participants.

Step 4 — Embed sentence (4) as a reduced relative clause modifying 'participants'The full clause would be "who had experienced childhood trauma." This is restrictive (it defines which participants), so no commas. We keep the full relative clause here because reducing to a past participle ("experienced") could be confused with a simple past-tense verb.

…500 participants who had experienced childhood trauma.

Step 5 — Assemble the final sentenceCombining all embedded structures into a single sentence yields a complex, information-rich construction that flows logically from agent to action to object to qualifier.

"Dr. Patel, a cognitive psychologist at Stanford, conducted a longitudinal study that tracked 500 participants who had experienced childhood trauma."

The final sentence packs four propositions into 22 words, compared with the 29 words of the four original sentences—a 24% reduction in length with no loss of information. More importantly, the hierarchical structure clearly signals which details belong to which noun: the appositive attaches to Dr. Patel, the first relative clause to study, and the second to participants. This is the precision that embedded structures afford.

SECTION 7

Strengths, Common Pitfalls, and Remedies

Like any syntactic tool, relative clauses and embedded phrases can be wielded skillfully or clumsily. This section examines both the rhetorical advantages and the common errors that writers encounter when embedding, along with concrete strategies for avoiding those errors.

Strengths and pitfalls of relative clauses and embedded phrases with remedies

Strength	Common Pitfall	Remedy
Combines related ideas into a single, cohesive sentence, reducing choppiness.	Over-embedding: Nesting three or more clauses creates a sentence too dense for the reader's working memory.	Limit embedding to two levels of nesting in most contexts. If a sentence requires a third level, split it.
Precisely targets detail to the noun that needs it, reducing ambiguity.	Misplaced modifier: Placing the clause or phrase far from the noun it modifies (e.g., "I saw the dog of the woman that was barking").	Position the embedded element immediately after the noun it modifies. Rearrange the main clause if necessary.
Enables concision by reducing full clauses to participial or appositive phrases.	Dangling participle: A participial phrase whose implied subject doesn't match the sentence's grammatical subject ("Running to class, the door was locked").	Ensure the implied subject of the participle matches the grammatical subject of the main clause, or rewrite using a full relative clause.
Signals the writer's sophistication and command of academic register.	Comma errors: Using commas with restrictive clauses or omitting them with non-restrictive clauses changes the meaning.	Apply the 'removal test': if removing the clause changes which noun you mean, it is restrictive (no commas); if not, it is non-restrictive (commas required).
Creates elegant variation in sentence length and structure.	Pronoun confusion: Using 'which' when 'who' is appropriate, or vice versa, or unclear antecedent reference.	Use 'who/whom/whose' for people and 'which/that' for things. If the antecedent is ambiguous, repeat the noun or restructure.

✦ KEY TAKEAWAY

Think of embedding like an engineer designing a load-bearing beam: a well-placed beam (relative clause) strengthens the entire structure (sentence), but stack too many beams in one spot and the structure becomes top-heavy and collapses under its own weight. The skill lies in knowing when one more embedded element adds elegance versus when it tips the sentence into confusion. A useful heuristic is the "read-aloud test"—if you cannot read the sentence aloud in a single breath without losing the thread, consider splitting it.

SECTION 8

Connections to Advanced Syntax and Rhetorical Strategy

The relative clause structures you have learned here are the gateway to more advanced syntactic maneuvers that characterize professional academic and literary writing. Understanding how basic embedding relates to these advanced techniques will allow you to continue developing your prose style well beyond this lesson.

How basic embedding connects to advanced syntactic and rhetorical strategies

Concept in This Lesson	Advanced Extension
Relative clause introduced by who, which, that	Free (nominal) relative clauses: "What the study revealed surprised the panel." The entire clause functions as a noun, not an adjective.
Single level of embedding (one clause inside another)	Center-embedding and recursion: Theoretical syntax explores how deeply humans can nest clauses. In practice, skilled writers use strategic recursion (two levels) while avoiding the garden-path effect.
Reduced relative clauses (participial phrases)	Absolute phrases: "Her argument having been dismantled, the senator yielded." These have their own subject + participle and modify the entire clause, not just a noun.
Restrictive vs. non-restrictive distinction	Sentential relative clauses: "The team won the grant, which surprised no one." Here 'which' refers to the entire preceding proposition, not a single noun.
Embedding for precision (academic register)	Periodic sentence structure: Classical rhetoric deliberately delays the main verb with layers of embedded phrases to build suspense and emphasis—a technique found in writers from Cicero to Toni Morrison.

As you continue to develop your writing, keep in mind that the recursive nature of language means there is theoretically no limit to how much information you can pack into a single sentence. The practical limit is cognitive: your reader must be able to hold the main clause's subject in working memory while processing embedded material. Advanced writers develop an intuitive feel for this threshold, varying sentence length and complexity to create a rhythm that is both informationally dense and pleasurable to read. The foundational tools of this lesson—relative clauses, participial phrases, and appositives—remain the workhorses of that endeavor even at the most advanced levels.

SECTION 9

Practice Problems

PROBLEM 1 — CONCEPTUAL

Explain the functional difference between a restrictive and a non-restrictive relative clause. Then write one sentence that uses a restrictive clause and another that uses a non-restrictive clause, both modifying the noun "researchers." Indicate which is which and explain how removing each clause affects the meaning.

PROBLEM 2 — BASIC

Combine the following two sentences into one using a relative clause: (a) "The algorithm processes data in real time." (b) "The algorithm was developed by a team at MIT." State whether your resulting relative clause is restrictive or non-restrictive, and explain your punctuation choice.

PROBLEM 3 — INTERMEDIATE

Reduce the following sentence by converting the relative clause into an embedded phrase (participial, appositive, or prepositional). Then explain what type of phrase you created and what was deleted: "The medication, which was approved by the FDA in 2022, has shown promising results in clinical trials that were conducted across twelve countries."

PROBLEM 4 — APPLIED

You are writing the introduction to a research paper on urban housing policy. Combine the following four sentences into one or two well-structured sentences using at least two different types of embedding (e.g., a relative clause and an appositive): (1) "Mayor Gonzalez announced a new housing initiative." (2) "She has served three terms in office." (3) "The initiative allocates $200 million to affordable housing." (4) "The funding comes from a recently passed bond measure."

PROBLEM 5 — CRITICAL THINKING

Consider the following sentence: "The students who were taught by the professor who had published the paper that challenged the theory that had dominated the field for decades performed better on the exam." Analyze the embedding structure: how many levels of nesting are present? Why does this sentence strain comprehension? Rewrite it as two or three sentences that preserve all the information while maintaining academic register, using a mix of relative clauses and reduced phrases.

SUMMARY

Summary — Relative Clauses & Embedded Phrases

Relative clauses are dependent clauses introduced by relative pronouns (who, whom, whose, which, that) or relative adverbs (where, when, why) that modify a noun in the main clause. Restrictive clauses (no commas, often introduced by 'that') are essential for identifying the noun, while non-restrictive clauses (set off by commas, introduced by 'which' or 'who') provide supplementary detail. Full relative clauses can be reduced to embedded phrases—participial phrases, appositives, and adjective phrases—by deleting the relative pronoun and any auxiliary verb, yielding more concise constructions.

The core writing skill is the embedding algorithm: identify a shared referent between two propositions, replace the shared noun with a relative pronoun, and insert the resulting clause immediately after the noun it modifies. Guard against over-embedding (more than two nesting levels), misplaced modifiers (clause too far from its antecedent), and dangling participles (implied subject mismatches). Mastering these structures enables you to write sentences that are simultaneously concise, precise, and rhythmically varied—hallmarks of effective academic and professional prose.