I understand that "that" can be either a relative pronoun or a subordinating conjunction, I just don't understand when. I know that both of these create dependent clauses, and I am pretty sure that subordinating conjunctions create adverb clauses (is this the same as the conjunction functioning as an adverb?) and that relative pronouns create noun and adjective clauses (again, is this the same as saying that the relative pronoun functions as a noun and an adjective?). I have been recently been working on doing some sentence analysis (breaking down a sentence into its constituent word forms and functions), and I have been told to bracket off the dependent clause that the relative pronoun starts in order to find its function. However, this is much more difficult to do with "that", since I don't know how to find out whether "that" is a relative pronoun or a conjunction, and I then don't know how to decide the function for the conjunction or relative pronoun of "that".

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    The grammatical term for the that which heads non-relative clauses, like She's thankful that you didn't buy it, is Complementizer, because these clauses, which function as subject or object clauses most often, are called Complement Clauses. That-clauses are one of the four types of complement clauses in English; the others are embedded questions, like I wonder where she went, infinitives like She wants to leave soon, and gerunds like She hates washing the sheets. Each is marked by its own complementizer. Commented Apr 17, 2021 at 2:25
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    Every sentence has at least one independent clause. But most independent clauses have many dependent clauses, so "complex" sentences, as they call them in elementary school, are by far the most common. As for dependent clauses, there are many, many types, and every language has its own set of clauses and rules for how they work. It's very complex and continues far beyond what you were apparently taught in school. Commented Apr 17, 2021 at 15:08
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    If you're seriously interested in how English grammar works, I can recommend McCawley 1998. It's not simple, but it's clear. Here's a summary handout from the syntax part of my Introduction to Linguistic Analysis class. And here are the coursepacks used as textbooks and workbooks for that class: Part 1 covers morphology, phonetics, and phonology, while Part 2 covers syntax, semantics, pragmatics, and selected short subjects. Commented Apr 17, 2021 at 15:14
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    You're starting off on the wrong foot. Despite what most dictionaries and some older grammars tell us, "that" is never a relative pronoun. Whether it is introducing a relative clause or a declarative content clause, it's a subordinator. The simplest way to distinguish the two kinds is to determine whether the clause has an element -- actually present or understood -- that is anaphoric to a preceding noun. If it has, then it's a relative clause; otherwise it's a declarative content clause. "I know the boy [that __ is late]" (relative clause) ~ "I know [that the boy is late]." (content clause).
    – BillJ
    Commented Apr 17, 2021 at 16:01
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    Despite what anyone tells us, that can be called a relative pronoun if the grammarian wishes to call it that. There is no absolute certainty about what category some chunk of language IS or ISN"T; there are only data and analyses. Categories and names come later, and are not imposed by fiat. Like any science, there is always considerable discussion and even dissent among grammarians. Anybody that lays down the law had better have more than one reference, and more than one argument. Many English speakers use that as a relative pronoun, and in their grammars that's what it is. Commented Apr 19, 2021 at 14:41

2 Answers 2


To presume that relative pronouns function as nouns and adjectives is faulty logic. They merely refer back to the antecedent, and the clauses they head are what really function as adjective clauses. And since conjunctions are merely connecting words, that as conjunction never refers back to antecedent as does the relative pronoun that. Once you go by this logic I'm sure you could tell one from the other lickety-split.


This is the book that Bill wrote. (Relative pronoun)


It's unlikely that he will succeed. (Conjunction)

  • So no antecedent = conjunction and antecedent = relative pronoun? I think I get this now. But what is the function of that as a conjunction vs. that as a relative pronoun? Commented Apr 17, 2021 at 0:40
  • Conjunctions only connect. They do no other job. [Relative] Pronouns are used in place of nouns. Thus, they can connect as well as refer back to some antecedent. But please note that relative adverbs can also connect as well as refer back to antecedents. However, they are not the same as relative pronouns.
    – user405662
    Commented Apr 17, 2021 at 0:44
  • But a conjunction must serve some function right? Pronouns can function as subjects, indirect objects, etc. What I'm getting at is that everything must have a function, so do conjunctions just function as... conjunctions? And isn't a relative adverb just a subordinating conjunction, and I'm sure that those don't have antecedents. I'm kind of confused here. Commented Apr 17, 2021 at 2:24
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    @TheeGrammarStallion In both constructions "that" is a subordinator, whose function is that of marker. Does that clear things up?
    – BillJ
    Commented Apr 17, 2021 at 12:58

You could apply a little trick to identify the role of "that" in any given sentence: replace it with "which" to understand whether the word serves as a conjunction or a relative pronoun.

Example 1: They said that four million workers stayed at home to protest against the tax.

Replacement with "which" does not make much sense in this case, so "that" is not used here as a relative pronoun but as a conjunction. That clauses are usually used in combination with verb -- said that, in this example -- or a noun or adjective. You can read more about this here.

Example 2: He went to the school that my father went to.

Replacement with "which" fits, so in this example "that" is a relative pronoun. More on relative pronouns here.

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    That works for restrictive relative clauses, where which (or who) can be used as a relative pronoun, and so can that. But it won't distinguish between complementizer that (I know that she's waiting for me) and demonstrative that (I know that woman's waiting for me), since neither one can substitute a Wh-word. Commented Apr 17, 2021 at 15:19
  • The solution differentiates a pronoun from a conjunction — the key confusion point for the OP. Commented Apr 19, 2021 at 13:19

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