A subordinating conjunction is a word or phrase that connects a dependent clause to an independent clause and expresses a relationship such as time, cause, condition, contrast, purpose, or place. Subordinating conjunctions also make the attached clause grammatically dependent, so the clause cannot function as a complete sentence by itself.
Key Facts at a Glance
- A subordinating conjunction introduces a dependent clause within a complex sentence.
- A dependent clause contains a subject and verb but cannot usually stand alone.
- An introductory dependent clause is normally followed by a comma.
- A dependent clause placed after an independent clause usually requires no comma.
- Because, although, if, when, while, before, and unless are common subordinating conjunctions.
- However and therefore are conjunctive adverbs, not subordinating conjunctions.
What Does a Subordinating Conjunction Do?
A subordinating conjunction performs two jobs: it connects clauses and signals the logical relationship between them. In Because the road flooded, the school closed, the word because identifies the road flooding as the reason for the school closing, while also making Because the road flooded dependent.
A subordinating conjunction does not merely add a transition between two ideas. It changes the grammatical status of one idea. Compare these forms:
- The road flooded. This is an independent clause.
- Because the road flooded. This is a dependent clause.
- Because the road flooded, the school closed. This is a complex sentence.
The main clause carries the sentence’s grammatical independence. The subordinate clause supplies context, such as when an action happened, why it happened, or under what condition it will happen.
Independent Versus Dependent Clauses
| Clause type | Required features | Example | Can stand alone? |
|---|---|---|---|
| Independent clause | Subject and finite verb; complete thought | The school closed. | Yes |
| Dependent clause | Subject and finite verb; subordinating marker | Because the road flooded | No |
| Independent clause | Subject and finite verb; complete thought | We left early. | Yes |
| Dependent clause | Subject and finite verb; condition marker | Although we were tired | No |
A dependent clause is sometimes called a subordinate clause. The terms describe the same grammatical unit, although subordinating conjunction names the connector that introduces it.
How Do Subordinating Conjunctions Build Sentences?
Subordinating conjunctions build complex sentences by attaching one dependent clause to one independent clause. Writers choose the conjunction first according to meaning, then decide which clause should receive emphasis and apply punctuation based on clause order.
Use these two basic formulas:
- Independent clause + subordinating conjunction + dependent clause
I stayed inside because the air quality was poor. - Subordinating conjunction + dependent clause, + independent clause
Because the air quality was poor, I stayed inside.
The meaning is nearly identical, but the emphasis changes. The first formula foregrounds the action. The second foregrounds the reason.
A Four-Step Construction Method
- Identify two related thoughts.
The power failed. We stopped the experiment. - Name the relationship.
The second event happened because of the first, so choose because. - Select the main clause.
If stopping the experiment matters most, write We stopped the experiment because the power failed. - Check punctuation and completeness.
If the dependent clause comes first, write Because the power failed, we stopped the experiment.
A useful editing test is to remove the conjunction. If the remaining words form a complete sentence, the original clause was probably independent. If they do not, the clause is dependent and needs a main clause.
What Are the Main Types of Subordinating Conjunctions?
Subordinating conjunctions are grouped by the relationship they express, not by a single universally fixed list. Some conjunctions have more than one meaning, so context determines whether since expresses time or cause and whether while expresses time or contrast.
| Relationship | Common conjunctions | Core question | Example |
|---|---|---|---|
| Time | after, before, when, while, until, whenever, once | When? | Call me when you arrive. |
| Cause | because, since, as, now that | Why? | We left because rain began. |
| Condition | if, unless, provided that, even if, assuming that | Under what condition? | We will go if the weather improves. |
| Contrast | although, though, even though, whereas, while | In spite of what? | Although it was late, we continued. |
| Purpose | so that, in order that, lest | For what aim? | Speak clearly so that everyone understands. |
| Place | where, wherever | Where? | Put the keys where I can find them. |
| Manner or comparison | as, as if, as though | How or like what? | He acted as though nothing happened. |
| Result | so…that, such…that | With what result? | The box was so heavy that we used a cart. |
Time Conjunctions
Time subordinators establish sequence, duration, or simultaneity. Before places one event earlier, after places it later, while indicates overlapping duration, and until marks the endpoint of an action.
- Before the meeting began, we reviewed the agenda.
- We reviewed the agenda before the meeting began.
- While the machine was running, the technician recorded its temperature.
- Wait here until the supervisor returns.
Since can mean from a past time to the present, as in I have worked here since 2021, or because, as in Since the store is closed, we will return tomorrow. When ambiguity matters, replace since with because or a specific time expression.
Cause Conjunctions
Cause subordinators explain reasons. Because is the clearest and most common choice, while since and as can sound less direct because they may also express time or manner.
| Conjunction | Typical meaning | Register | Example |
|---|---|---|---|
| because | Direct reason | Neutral | The flight was delayed because fog reduced visibility. |
| since | Reason already known or evident | Neutral to formal | Since the data changed, recalculate the result. |
| as | Reason, often background information | Neutral to formal | As demand increased, prices rose. |
| now that | New condition causing action | Neutral | Now that the test is complete, archive the files. |
| inasmuch as | Formal stated reason | Formal | The claim is limited inasmuch as evidence is incomplete. |
Use because when readers might otherwise misunderstand the relationship. Clear causal wording is usually preferable to a more formal connector that introduces ambiguity.
Conditional Conjunctions
Conditional subordinators state requirements, exceptions, or hypothetical situations. If introduces a possible condition, while unless means if not.
- If the temperature falls, the pipes may freeze.
- Unless the temperature rises, the pipes may freeze.
- You may enter provided that you show identification.
- Even if the forecast changes, the event will continue.
- In case the alarm sounds, use the west exit.
A common error is using unless with an additional negative that reverses the intended meaning. Unless you do not call technically means if you do call, although readers may need to reread it. Prefer unless you call or if you do not call.
Contrast and Concession Conjunctions
Contrast subordinators connect an expected circumstance with an unexpected result. Although, though, and even though introduce concession; whereas and while commonly compare two contrasting facts.
- Although the sample was small, the pattern was consistent.
- Even though the route was longer, it was safer.
- Whereas the first model uses steel, the second uses aluminum.
- While the north side receives sunlight, the south side remains shaded.
Though is less formal than although and can appear at the end of a sentence: The plan is expensive, though. In that final position, though functions more like an adverb than a clause-introducing subordinating conjunction.
Where Does the Comma Go?
A dependent clause at the beginning of a sentence is normally followed by a comma, while a dependent clause after an independent clause normally receives no comma when the relationship is essential to the sentence’s meaning.
| Clause order | Standard punctuation | Example |
|---|---|---|
| Dependent first | Comma after dependent clause | If you call me, I will answer. |
| Independent first | Usually no comma | I will answer if you call me. |
| Dependent first, short clause | Comma is often retained | When ready, press the button. |
| Interrupted main clause | Commas around interruption | The device, when fully charged, records data. |
The comma after an introductory dependent clause helps readers identify the boundary between the subordinate and main clauses. In short sentences, punctuation can vary by style and rhythm, but omitting the comma may slow comprehension.
Essential and Nonessential Meaning
A clause that identifies which person or thing the sentence means is essential and usually does not take commas. A clause that adds parenthetical information is nonessential and is set off with commas.
- Use the file that contains the final results.
The clause identifies the file. - Use the final results file, which contains the revised figures.
The clause adds extra information.
This distinction is more often discussed with relative clauses, but the same principle helps explain why punctuation depends on meaning rather than on a mechanical pause alone.
Which Words Are Often Confused With Subordinating Conjunctions?
Subordinating conjunctions introduce dependent clauses, but several other connectors express relationships without performing that exact grammatical job. Conjunctive adverbs, coordinating conjunctions, and prepositions require different structures and punctuation.
| Connector category | Examples | What follows? | Correct model |
|---|---|---|---|
| Subordinating conjunction | because, although, if | Clause | We left because it rained. |
| Coordinating conjunction | and, but, or, so | Word, phrase, or clause | It rained, so we left. |
| Correlative conjunction | either…or, neither…nor | Parallel elements | Either walk or wait. |
| Conjunctive adverb | however, therefore, consequently | Independent clause | It rained; therefore, we left. |
| Preposition | because of, despite, during | Noun phrase or gerund | We left because of rain. |
Subordinating Conjunctions Versus FANBOYS
The coordinating conjunctions for, and, nor, but, or, yet, so, commonly remembered as FANBOYS, join grammatically equal elements. When a FANBOYS conjunction joins two independent clauses, place a comma before it.
- The road flooded, so the school closed.
- Because the road flooded, the school closed.
The first sentence has two independent clauses joined by so. The second has one dependent clause introduced by because and one independent clause. These structures are not interchangeable in punctuation or clause hierarchy.
Subordinating Conjunctions Versus Conjunctive Adverbs
However, therefore, instead, and consequently are conjunctive adverbs, not subordinating conjunctions. They cannot normally join two independent clauses with only a comma.
- Incorrect: The road flooded, therefore the school closed.
- Correct: The road flooded; therefore, the school closed.
- Correct: The road flooded, so the school closed.
- Correct: Because the road flooded, the school closed.
The semicolon joins the independent clauses, while the comma after therefore marks the adverb’s position within the second clause.
Can a Preposition Replace a Subordinating Conjunction?
A prepositional phrase can often express a similar relationship, but a preposition must be followed by a noun phrase, pronoun, or gerund rather than a finite clause. This difference matters when rewriting sentences.
| Subordinating form | Prepositional alternative | Structural difference |
|---|---|---|
| because it rained | because of the rain | Clause versus noun phrase |
| although she was tired | despite her fatigue | Clause versus noun phrase |
| after we finished | after finishing | Finite clause versus gerund phrase |
| before the team arrived | before the team’s arrival | Clause versus possessive noun phrase |
| while he was driving | during his drive | Clause versus noun phrase |
Do not write because of it rained or despite she was tired in standard English. Use because it rained, because of the rain, although she was tired, or despite her fatigue.
How Do You Use Subordinating Conjunctions Clearly?
Choose a conjunction whose meaning is specific enough for the reader to identify the relationship immediately. Place the main clause where you want emphasis, and test whether the dependent clause attaches logically to the correct verb or noun.
Use this practical checklist:
- Name the relationship: time, reason, condition, contrast, purpose, place, or result.
- Choose the narrowest accurate connector: use because instead of ambiguous as when the reason matters.
- Check clause completeness: ensure the dependent clause has a main clause.
- Place the dependent clause deliberately: opening position frames context; closing position foregrounds the action.
- Apply punctuation: add a comma after an introductory dependent clause.
- Read for attachment: confirm that the subordinate clause modifies the intended action.
- Check register: use although in formal writing when though would sound conversational.
An important practitioner rule is to avoid selecting conjunctions by memorized lists alone. Meaning comes first. A sentence with a familiar conjunction can still be illogical if the connector expresses the wrong relationship.
How Does Clause Placement Change Emphasis?
Clause placement changes information flow without necessarily changing factual meaning. Writers often put familiar background information in the dependent clause and new or important information in the independent clause.
- Although the budget was limited, the project succeeded.
- The project succeeded although the budget was limited.
The first version frames success as unexpected. The second version presents success first and adds the budget limitation afterward. In reports, instructions, and academic prose, this choice controls emphasis and reader expectations.
What Common Errors Should You Fix?
The most frequent errors are sentence fragments, comma splices, double conjunctions, and ambiguous connector choices. Each problem results from confusing logical connection with grammatical completeness.
Sentence Fragments
- Incorrect: Although the equipment was new.
- Correct: Although the equipment was new, it failed during testing.
The first example contains a subject and verb, but although prevents the clause from expressing a complete sentence.
Double Conjunctions
Do not normally combine although and but for the same contrast.
- Incorrect: Although the road was icy, but we continued.
- Correct: Although the road was icy, we continued.
- Correct: The road was icy, but we continued.
The same principle applies to because and so when one relationship is enough: Because the server failed, we restarted it, or The server failed, so we restarted it.
Comma Splices
A comma cannot independently join two main clauses.
- Incorrect: The alarm sounded, we evacuated.
- Correct: When the alarm sounded, we evacuated.
- Correct: The alarm sounded, and we evacuated.
- Correct: The alarm sounded; we evacuated.
Misplaced or Ambiguous Modification
Place the subordinate clause near the action it modifies.
- Ambiguous: When entering the laboratory, the lights should be switched on.
- Clear: When you enter the laboratory, switch on the lights.
The original sentence makes the lights appear to be entering the laboratory. Adding the intended subject removes the faulty attachment.
Are There Advanced Alternatives?
Advanced writers can replace some subordinate clauses with participial phrases, infinitive phrases, noun phrases, or separate sentences, but the alternatives change emphasis and sometimes reduce clarity. Shorter structures are not automatically better.
- Because the trial ended early, researchers published the findings.
- After ending the trial early, researchers published the findings.
- To preserve the evidence, researchers sealed the samples.
- The trial ended early. Researchers published the findings.
Participial phrases require a shared, clearly understood subject. After ending the trial early, the findings were published is faulty because the findings did not end the trial.
Subordinating conjunctions are especially useful when the relationship itself matters. They make cause, condition, timing, and concession explicit. They are less useful when a simple sentence communicates the idea more precisely.
What Should ESL Writers Know?
ESL writers should learn subordinating conjunctions by meaning and sentence pattern rather than by alphabetic memorization. The most useful first group is because, if, when, before, after, although, and unless, followed by practice reversing clause order.
Some distinctions require special attention:
- Although takes a clause: Although he was tired, he worked.
- Despite takes a noun phrase or gerund: Despite his fatigue, he worked.
- Because takes a clause: Because traffic was heavy, she was late.
- Because of takes a noun phrase: Because of heavy traffic, she was late.
- Unless already contains a negative condition: Unless you hurry, you will miss the train.
A reliable exercise is sentence transformation. Rewrite I stayed home because I was ill as Because I was ill, I stayed home, then replace because with although, if, or while and explain how the meaning changes.
Frequently Asked Questions
Is “because” a subordinating conjunction?
Yes. Because is a subordinating conjunction when it introduces a clause that gives the reason for an independent clause, as in We canceled the picnic because rain was forecast. The phrase because of is different: it is a preposition and must be followed by a noun phrase, as in We canceled the picnic because of rain.
Can a subordinating conjunction start a sentence?
Yes. A subordinating conjunction can start a sentence when it introduces a dependent clause, but the dependent clause must be followed by an independent clause. Write Although the test was difficult, most students finished, not Although the test was difficult as a standalone sentence.
Do subordinating conjunctions always require commas?
No. An introductory dependent clause is normally followed by a comma, as in If the weather improves, we will leave. A dependent clause placed after the main clause usually has no comma when it is essential to the meaning: We will leave if the weather improves.
Is “that” a subordinating conjunction?
That can function as a subordinating conjunction, also called a complementizer, when it introduces a noun clause: She knew that the report was incomplete. In that sentence, that the report was incomplete functions as the object of knew, rather than expressing time, cause, or condition.
What is the difference between “although” and “despite”?
Although introduces a finite clause containing a subject and verb: Although the plan was expensive, we approved it. Despite is a preposition and introduces a noun phrase or gerund: Despite the expense, we approved it or Despite being expensive, the plan was approved.
What is the easiest way to identify one?
Find the connector, then inspect the words after it. If the connector introduces a subject and finite verb while making that clause unable to stand alone, it is probably subordinating the clause. Finally, check that the sentence also contains an independent clause.
The Bottom Line
Subordinating conjunctions connect dependent clauses to independent clauses and show relationships such as cause, time, condition, contrast, purpose, and place. The most reliable method is to identify the relationship, choose a precise connector, check clause completeness, and place a comma after an introductory dependent clause. Understanding what are subordinating conjunctions means understanding both their meanings and their effect on sentence structure.
