Definition · Plain-language
Subordinating conjunctions
A subordinating conjunction is a word that joins a dependent (subordinate) clause to an independent clause, showing how the two ideas relate — words such as because, although, since and while.
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What they do
A subordinating conjunction does two jobs at once: it connects two clauses, and it makes one of them dependent — that is, unable to stand alone as a complete sentence. Take "although the results were promising": by itself this is a fragment, because although forces the clause to lean on a main clause for completion ("although the results were promising, the sample was small"). The conjunction also tells the reader how the two ideas relate. Because and since signal cause; although and whereas signal contrast; if and unless signal condition; when, after and while signal time. This is what distinguishes subordinating conjunctions from coordinating conjunctions, which join equal, independent elements.
A working list by relationship
Subordinating conjunctions group neatly by the relationship they express. Time: after, before, when, while, until, since, as soon as. Cause and reason: because, since, as, now that. Condition: if, unless, provided that, in case. Contrast and concession: although, though, even though, whereas, while. Purpose and result: so that, in order that. Place: where, wherever. Some words, such as since and while, belong to more than one group — "since" can mean either "because" or "from the time that", and context decides. Learning these by relationship, rather than memorising a flat list, makes it easier to pick the right connector when writing.
Comma rules and sentence position
A subordinate clause can come before or after the main clause, and its position changes the punctuation. When the subordinate clause comes first, it is followed by a comma: "Because the deadline moved, we revised the plan." When it comes second, you usually do not need a comma: "We revised the plan because the deadline moved." There is a subtlety with contrast words like although and whereas, which often take a comma even when they follow the main clause. Getting this right keeps complex sentences readable. Mishandling it produces two common errors — the comma splice and the sentence fragment — so the subordinating conjunction is a key tool for joining ideas correctly.
Key facts
At a glance
- Definition: a word that joins a dependent clause to an independent clause
- Effect: makes its clause dependent — it cannot stand alone
- Shows: cause, time, condition, contrast, purpose or place
- Common examples: because, although, since, while, if, when, unless, after
- Comma rule: comma after a leading subordinate clause; usually none when it follows
- Contrast with: coordinating conjunctions (and, but, or), which join equals
Common misconceptions
What people often get wrong
Often heard: A clause beginning with a subordinating conjunction is a complete sentence.
Actually: It is a dependent clause and a fragment on its own. "Because it was late" needs a main clause to finish the thought, such as "Because it was late, we left."
Often heard: You always put a comma before a subordinating conjunction.
Actually: The comma usually depends on position. A subordinate clause that comes first takes a comma after it; one that follows the main clause usually takes no comma, as in "we left because it was late".
Often heard: "And", "but" and "or" are subordinating conjunctions.
Actually: Those are coordinating conjunctions, which join elements of equal rank. Subordinating conjunctions, such as because and although, instead make one clause dependent on another.
Going deeper
