A subordinating conjunction introduces a dependent (subordinate) clause and connects it to an independent (main) clause, showing the logical relationship between the two — time, reason, condition, contrast, or purpose. For example, in After the show ended, we went home, after introduces a time relationship between the dependent clause and the main clause. Unlike coordinating conjunctions (and, but, or), which join elements of equal grammatical status, a subordinating conjunction creates a clause that cannot stand alone. Reference grammars such as the Cambridge Grammar classify subordinating conjunctions by the meaning relationship they express.
What Is a Subordinating Conjunction?
A subordinating conjunction can introduce a clause at the start or in the middle of a sentence. The dependent clause it introduces is never a complete sentence on its own — it needs the main clause to make sense.
- Because it was raining, we stayed inside. (dependent clause first, comma required)
- We stayed inside because it was raining. (dependent clause second, no comma)
- Although she was tired, she finished the report.
Formation Table: Subordinating Conjunctions by Function
| Function | Conjunctions | Example |
|---|---|---|
| Time | when, while, before, after, until, since, as soon as | Before you leave, turn off the lights. |
| Reason | because, since, as | She left early because she felt ill. |
| Condition | if, unless, provided that, as long as | I’ll come if I finish work early. |
| Contrast / concession | although, though, even though, whereas, while | Although it was expensive, they bought it. |
| Purpose | so that, in order that | She whispered so that no one would hear. |
| Manner | as, as if, as though | He behaved as if nothing had happened. |
Subordinating vs. Coordinating Conjunctions
Coordinating conjunctions (and, but, or, so, yet, for, nor — remembered as FANBOYS) join two independent clauses of equal weight. Subordinating conjunctions join a dependent clause to an independent one, making the dependent clause grammatically reliant on the main clause.
- Coordinating: She was tired, so she went to bed. (two equal, independent clauses)
- Subordinating: Because she was tired, she went to bed. (the first clause cannot stand alone)
Punctuation Rule
Use a comma after the dependent clause only when it comes before the main clause. When the dependent clause follows the main clause, no comma is generally needed.
- When the meeting ended, everyone left. (comma required)
- Everyone left when the meeting ended. (no comma)
Common Mistakes
- Wrong: Although he was tired, but he kept working. Correct: Although he was tired, he kept working. (never combine ‘although’ with ‘but’ in the same sentence — this is a redundant double connector)
- Wrong: Because she was late. She missed the bus. Correct: Because she was late, she missed the bus. (a subordinate clause alone, without a main clause, is a sentence fragment)
- Wrong: We went home, because it was raining and, so we got wet. Correct: We went home because it was raining, and we got wet. (do not overload one sentence with both a subordinating and a coordinating conjunction pointing at the same idea)
- Wrong: Unless if you hurry, you’ll be late. Correct: Unless you hurry, you’ll be late. (‘unless’ already means ‘if not’, so combining it with ‘if’ is redundant)
Practice Exercises
Grammar Quiz
Choose the correct subordinating conjunction for each context.
Cloze Dropdown
Select the conjunction that matches the function — time, reason, contrast.
Complete the Sentence
Join a main clause and dependent clause with the right conjunction.
Match-Up
Match subordinating conjunctions to their function group.
Flash Cards
Drill subordinating conjunctions by function with instant feedback.
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Frequently Asked Questions
What is a subordinating conjunction?
A subordinating conjunction introduces a dependent clause and connects it to a main clause, showing a relationship such as time, reason, condition, contrast, or purpose. Examples include because, although, if, when, and since.
What is the difference between a subordinating and a coordinating conjunction?
Coordinating conjunctions (and, but, or, so, yet, for, nor) join two independent clauses of equal weight. Subordinating conjunctions (because, although, if, when) join a dependent clause to an independent one, making the dependent clause unable to stand alone.
Can a clause introduced by a subordinating conjunction stand alone as a sentence?
No. A clause beginning with a subordinating conjunction is a dependent clause and cannot form a complete sentence by itself. ‘Because she was late.’ is a sentence fragment; it must be attached to a main clause: Because she was late, she missed the bus.
Do I need a comma with a subordinating conjunction?
Yes, when the dependent clause comes before the main clause: When the meeting ended, everyone left. No comma is generally needed when the dependent clause follows the main clause: Everyone left when the meeting ended.
Is ‘although…but’ correct?
No. Combining ‘although’ with ‘but’ in the same sentence is a redundant double connector, since both words signal contrast. Use one or the other: Although he was tired, he kept working, or He was tired, but he kept working.
What subordinating conjunctions express condition?
If, unless, provided that, as long as, and on condition that all introduce conditional clauses: I’ll come if I finish work early; You can go out as long as you finish your homework. ‘Unless’ already means ‘if not’, so it should never be combined with ‘if’.
Can ‘while’ introduce contrast as well as time?
Yes. ‘While’ can mean ‘during the time that’ (While I was cooking, the phone rang) or ‘in contrast to the fact that’ (While I understand your concern, I cannot agree). Context makes the intended meaning clear.
What is the difference between ‘as’ and ‘as if’?
‘As’ can mean ‘because’ or ‘while’, depending on context. ‘As if’ (and ‘as though’) introduces a clause of manner or comparison, often describing something that is not true or is uncertain: He behaved as if nothing had happened, frequently followed by a past subjunctive form for hypothetical comparisons.
Can more than one subordinating conjunction appear in the same sentence?
Yes, complex sentences can contain multiple dependent clauses, each with its own subordinating conjunction: Although it was late, she kept working because the deadline was the next morning. Each dependent clause must still relate clearly back to the main clause.
Why are subordinating conjunctions important for exam writing?
Varying subordinating conjunctions instead of repeatedly using ‘because’ or ‘if’ demonstrates grammatical range, a key criterion in IELTS and Cambridge writing assessments. Correctly punctuating dependent and main clauses also avoids sentence fragments and comma splices, both penalised as accuracy errors.