Relative Clause

Definition:

A relative clause is a subordinate clause that modifies a noun or noun phrase, restricting or elaborating its reference. In “the book that I borrowed from the library,” the italicized portion is a relative clause modifying the book. Relative clauses are introduced in English by relative pronouns (that, which, who, whom, whose) or may appear with the pronoun omitted (“the book I borrowed”). Across languages, relative clause structures vary enormously in their position, marking, and what kinds of nouns they can modify — making them one of the most typologically interesting and pedagogically important clause types in second language acquisition.

In-Depth Explanation

Basic structure: A relative clause contains a gap — a position inside it that refers back to the noun being modified (the head noun or antecedent). In “the woman who won the prize,” the relative clause who won the prize has who filling the subject position. In “the prize that she won,” that fills the object position. The head noun (the woman, the prize) is simultaneously the antecedent of the relative pronoun and the main-clause referent.

Restrictive vs. non-restrictive:

These are the two main types of relative clauses English teachers typically introduce:

Restrictive: Limits the set of possible referents. “The dog that bit me” is a specific dog — not just any dog. No commas. Use that or which (in American English, prescriptivists prefer that for restrictive).
Non-restrictive: Adds supplementary information about an already-identified referent. “My sister, who lives in Tokyo, just called.” The relative clause is parenthetical — remove it and the meaning is intact. Must use commas and which/who, never that.

Accessibility hierarchy: Cross-linguistic research by Keenan and Comrie (1977) established the Noun Phrase Accessibility Hierarchy — a typological ranking of which grammatical positions can be relativized across languages:

> Subject > Direct Object > Indirect Object > Oblique > Genitive > Object of Comparison

Languages that can relativize a lower position on the hierarchy can also relativize all higher positions. English can relativize all positions (though genitives require whose). Some languages can only relativize subjects, others only subjects and objects. This hierarchy predicts learner error patterns — learners from languages with restricted relativization struggle with lower-position relative clauses in the target language.

Pre-nominal vs. post-nominal: One of the largest typological divides in relative clause structure. In English and most European languages, relative clauses are post-nominal — they come after the head noun: “the book [that I read].” In Japanese, Korean, Turkish, and many other SOV languages, relative clauses are pre-nominal — they come before the head noun, and they use no relative pronoun:

> Japanese: [私が昨日読んだ] 本 (lit. “[I-yesterday-read] book” = “the book that I read yesterday”)

This means the entire phrase that modifies the noun precedes it, and the relative clause is marked only by a final verb in the attributive (連体形, rentaikei) form. There is no equivalent to English that or which. For English L1 learners of Japanese, this requires restructuring not just a syntactic pattern but the entire way sentence embedding is conceived — the noun comes last, after everything that modifies it.

Zero relativization: Many languages, and even English in certain registers, allow the relative pronoun to be omitted when the gap is in object position: “the book (that) I read” → “the book I read.” Zero relativization is common in spoken English but restricted in formal writing.

History

Relative clauses have been analyzed since antiquity — the Greek grammarians noted that relative pronouns (ὅς, ἥ, ὅ) introduced subordinate clauses. In modern linguistics, the formal analysis of relative clauses became central to generative grammar: transformationalists analyzed them as derived from embedded sentences, with relative pronouns being movement traces. Later, in Government and Binding theory and Minimalism, the left-periphery of relative clauses (Spec, CP) was the site of relative pronoun movement.

The cross-linguistic typology of relative clauses was systematically documented by Keenan and Comrie in their foundational 1977 Language paper, which introduced the Accessibility Hierarchy. This remains one of the most replicated findings in linguistic typology and has had major influence on SLA research — particularly on the acquisition order of different relativized positions.

Common Misconceptions

“Use that for things and who for people.” A widely taught rule in English, but “the company that I work for” and “the company which I work for” are both standard. The that/which distinction in American English is actually about restrictive vs. non-restrictive.
“Japanese doesn’t have relative clauses.” Japanese has fully productive relative clauses — they just look radically different from English ones. The pre-nominal position and absence of a relative pronoun don’t make them “not real” relative clauses.
“Relative clauses are advanced grammar.” They are formally complex but appear in early child language acquisition and in basic daily speech (“the thing I told you about”). Learners use them implicitly before analyzing them explicitly.
“You can always drop that.” Only in object-gap relativization. “The woman that left” → you cannot drop that because it fills the subject position: “The woman left” changes the meaning.

Criticisms

Most SLA research on relative clause acquisition supports the Accessibility Hierarchy’s predictions — subject relatives are acquired before object relatives, etc. However, some researchers have questioned whether the hierarchy is truly universal or whether instruction can override the predicted order. Processing-based accounts (e.g., O’Grady’s linear parsing model) offer alternative explanations for learner difficulty with relative clauses that don’t appeal to abstract syntactic hierarchies — and account for why center-embedded relatives (“The rat the cat the dog chased ate died”) are nearly incomprehensible despite being grammatical.

Social Media Sentiment

Relative clauses are one of the most-discussed grammar topics on r/LearnJapanese — the pre-nominal structure trips up virtually every beginner, and many learners report that understanding it “clicked” as a major milestone. Common discussion points include parsing long nominal chains where multiple relative clauses are stacked before the head noun. On r/languagelearning, the difficulty varies widely by L1: learners of Turkish or Korean find Japanese relative clauses intuitive, while English, French, and Spanish speakers require a mental restructuring.

Practical Application

For English learners: Master the that/which/who system and learn to recognize the gap inside the clause that connects back to the head noun. Practice identifying the antecedent and the role the relativized element plays inside the clause (subject, object, oblique).

For Japanese learners: This is one of the highest-value structural patterns to internalize. Key points:

The relative clause comes before the noun it modifies.
There is no relative pronoun — the clause ends in a verb in the attributive form (連体形).
Practice by building up from short modifiers: 読んだ本 → 昨日読んだ本 → 図書館で昨日読んだ本 (the book I read yesterday at the library)
Reading extensive Japanese — rather than studying grammar rules — is the most efficient way to internalize pre-nominal relative clauses. Immersion methods and extensive reading are particularly effective here.

Related Terms

Research

Keenan, E. L., & Comrie, B. (1977). Noun phrase accessibility and universal grammar. Linguistic Inquiry, 8(1), 63–99. [Introduced the Accessibility Hierarchy — the foundational typological study of relative clause formation across languages]
Doughty, C. (1991). Second language instruction does make a difference. Studies in Second Language Acquisition, 13(4), 431–469. [Examined whether instruction accelerates relative clause acquisition in English L2]
Ozeki, H., & Shirai, Y. (2007). Does the accessibility hierarchy predict the difficulty order in the acquisition of Japanese relative clauses? Studies in Second Language Acquisition, 29(2), 169–196. [Applies the accessibility hierarchy to Japanese L2 learners; nuanced findings]
O’Grady, W. (2005). Syntactic Carpentry: An Emergentist Approach to Syntax. Erlbaum. [Linear parsing account of relative clause processing difficulty]