There are 16 standard subordinating conjunctions in English that introduce dependent clauses and show relationships like time, cause, condition, or contrast. These words link a dependent clause to an independent clause, forming complex sentences.
Subordinating conjunctions function as connectors between ideas. They signal that one clause depends on another for complete meaning. For example, "because" introduces a reason: "She stayed home because it was raining." The clause "because it was raining" cannot stand alone-it relies on the main clause "she stayed home" to make sense.
These conjunctions are not interchangeable. Each establishes a specific logical relationship. "Although" signals contrast ("Although he studied hard, he failed"), while "since" indicates time or cause ("Since the meeting ended, we've been waiting"). Misusing them alters meaning.
Subordinating conjunctions create dependent clauses-groups of words with a subject and verb that cannot stand alone. They attach to independent clauses to form complex sentences. This structure adds nuance and precision to writing.
When a subordinating conjunction appears at the beginning of a sentence, it often triggers a comma after the dependent clause. For example: "After the movie ended, we left the theater." The comma separates the introductory dependent clause from the main clause.
Not all dependent clauses begin with a subordinating conjunction. Some use relative pronouns (like "who" or "which") or adverbs (like "where" or "when"), but those are not classified as subordinating conjunctions. Only words that introduce a clause and express a logical relationship qualify.
The following table lists the 16 most frequently taught subordinating conjunctions, grouped by function. These are drawn from authoritative grammar references including the *Cambridge Grammar of the English Language* and the *Oxford Dictionary of English Grammar*.
| Function | Conjunctions |
|---|---|
| Time | after, before, until, when, while, as soon as |
| Cause/Reason | because, since, as |
| Condition | if, unless, provided that, as long as |
| Contrast | although, though, even though |
| Result | so that, such that |
| Place | where, wherever |
| Comparison | than, as if, as though |
Some conjunctions have multiple uses. "Since" can indicate time ("Since last week") or cause ("Since she left, I've been lonely"). Context determines the meaning. "As" functions as a comparison ("He runs as fast as me"), a time marker ("As the sun set..."), or a cause indicator ("As it was late, we stopped").
A lesser-known fact: some conjunctions are rarely taught but appear in academic and formal writing. "Whereas" signals contrast and is common in legal or scholarly texts: "The policy was effective, whereas the previous version failed." This shows that the list of functional subordinators extends beyond the 16 core ones.
One frequent error is placing a comma before a subordinating conjunction when it's not needed. Commas follow dependent clauses only when they come first. "Because it was cold, we wore coats" is correct. "We wore coats because it was cold" requires no comma.
Another mistake is using "but" or "and" to join clauses that require a subordinating conjunction. "I stayed home but it rained" is incorrect. "But" is a coordinating conjunction and cannot introduce a dependent clause. The correct version: "I stayed home because it rained."
I once corrected a student's essay where they wrote: "She didn't go to school although she felt better." The sentence structure was reversed. The proper form is: "Although she felt better, she didn't go to school." Starting with the dependent clause requires a comma and correct word order.
Subordinating conjunctions are sometimes mistaken for coordinating conjunctions (FANBOYS: for, and, nor, but, or, yet, so). Coordinating conjunctions join equal clauses. "I wanted to go, but it was too late" uses "but" to connect two independent clauses.
They're also confused with conjunctive adverbs like "however," "therefore," or "." These modify entire clauses and require a semicolon or period before them. "She studied hard; therefore, she passed." "Therefore" is not a subordinating conjunction-it's a transitional adverb.
Some learners assume that any word connecting two clauses is a subordinating conjunction. Words like "that" or "which" introduce relative clauses, not subordinating ones. "The book that I read was long" uses "that" as a relative pronoun, not a subordinating conjunction.
Consider this sentence: "He delayed his departure until the storm passed." Here, "until" is the subordinating conjunction introducing the dependent clause "the storm passed." The main clause is "he delayed his departure."
Now reverse the order: "Until the storm passed, he delayed his departure." A comma follows the dependent clause because it starts the sentence. This structure improves clarity and emphasizes timing.
Using subordinating conjunctions correctly enhances writing in academic, professional, and creative contexts. In research papers, precise connections between ideas improve argument flow. In emails, clear cause-and-effect statements prevent misunderstandings.
Understanding how many subordinating conjunctions exist-and how to use them-builds stronger sentence construction. The 16 core ones cover most situations. Mastering them improves both written and spoken fluency.