Subordinating Conjunctions: Rules, Types and Examples

Overview

A subordinating conjunction introduces a dependent clause, a clause that has a subject and a verb but cannot stand alone as a complete sentence. The conjunction connects that dependent clause to a main clause, and in doing so it signals the exact nature of the relationship between them: a cause, a condition, a contrast, a time, or a purpose.

What makes subordinating conjunctions distinct from coordinating conjunctions is the relationship of dependence they create. A coordinating conjunction joins two elements of equal rank. A subordinating conjunction makes one clause subordinate to the other, meaning the dependent clause needs the main clause to complete its meaning. On its own, because the flight was delayed is not a sentence. It raises a question the reader expects the main clause to answer.

What Subordinating Conjunctions Signal

Different subordinating conjunctions signal different kinds of relationships. Grouping them by meaning makes them easier to learn and apply.

Time

Time conjunctions establish when one action occurs in relation to another. Common examples include when, before, after, while, since, until, and as soon as.

Cause and Reason

Cause conjunctions explain why the main clause situation exists or occurs. The most common are because, since, and as. All three signal reason, but they differ in formality and in how directly they state the cause.

Because is the most direct and most common. Since and as carry a softer implication, suggesting the reason is already known or obvious to the reader.

Condition

Condition conjunctions introduce a clause that must be true for the main clause to apply. The most common are if, unless, provided that, and as long as.

Contrast and Concession

Contrast conjunctions introduce an idea that is unexpected given what the main clause states. Common examples are although, even though, though, and whereas.

Although and even though are close in meaning, but even though carries stronger emphasis. Whereas signals a direct contrast between two situations or people, often highlighting a difference rather than a surprise.

Purpose

Purpose conjunctions explain why an action is taken or what outcome it aims to produce. The most common at this level are so that and in order that.

Result

So...that and such...that introduce a result clause, showing that the degree or quality described in the main clause led to a particular outcome.

Clause Order and Comma Rules

The dependent clause can appear either before or after the main clause. Its position determines whether a comma is required.

Rule 1: When the dependent clause comes first, place a comma after it and before the main clause.

Rule 2: When the main clause comes first and the dependent clause follows, no comma is needed in most cases.

The meaning of both versions is the same. Whichever idea appears at the beginning of the sentence receives slightly more prominence.

Subordinating vs. Coordinating Conjunctions

A coordinating conjunction cannot move: she was tired but she stayed cannot become but she was tired she stayed. A subordinating conjunction moves with its clause: both although she was tired, she stayed and she stayed although she was tired are correct.

Common Mistakes to Avoid

Mistake 1: Treating a Dependent Clause as a Complete Sentence

A dependent clause introduced by a subordinating conjunction is a fragment. It must attach to a main clause.

Mistake 2: Omitting the Comma After a Fronted Dependent Clause

When the dependent clause opens the sentence, a comma must follow it.

Mistake 3: Using Although and But Together

Although and but both signal contrast, but they belong to different conjunction types. Using them together in the same clause creates a double conjunction error. Only one is needed.

Mistake 4: Confusing Because and Because Of

Because is a conjunction and introduces a full clause with a subject and verb. Because of is a preposition and introduces a noun phrase.

Mistake 5: Placing a Comma Before the Dependent Clause When It Comes Second

When the main clause comes first and the dependent clause follows, no comma is needed before the subordinating conjunction.

Mistake 6: Using Since to Mean Time and Cause in the Same Sentence

Since can signal both a time relationship and a reason, which occasionally creates ambiguity. When both readings are possible, choosing because for cause or after for time removes the confusion.

Practice Exercises

Exercise 1: Choose the Correct Subordinating Conjunction

Choose the conjunction that best fits the meaning of each sentence.

1. _______ the storm was forecast, the organisers moved the event indoors. (Because / Although)
2. She will not sign the contract _______ the terms are revised. (unless / while)
3. He checked the figures twice _______ there were no errors in the final report. (so that / whereas)
4. _______ he has worked here for ten years, he still asks for feedback regularly. (Since / Although)
5. The team worked through the night _______ the deadline could be met. (so that / until)

Exercise 2: Rewrite Each Sentence by Moving the Dependent Clause

Each sentence has the dependent clause after the main clause. Rewrite it with the dependent clause first and add a comma where needed.

1. She called ahead because the office might be closed.
2. He took extra notes while the lecturer was speaking.
3. The plan will succeed if everyone commits to it.
4. They chose a smaller venue since attendance was lower than expected.
5. She read the contract carefully before she signed anything.

Exercise 3: Correct the Error

Each sentence contains one error related to subordinating conjunctions. Identify and correct it.

1. Although the weather was perfect. The match was cancelled.
2. Even though the project took longer, but the results were worth it.
3. She missed the meeting because of she forgot to set an alarm.
4. He stayed at the office, because he needed to finish the report.
5. Since the equipment arrived the team has been testing it daily.

Summary

Subordinating conjunctions allow complex ideas to be expressed within a single, well-ordered sentence. Knowing which conjunction signals which relationship, applying the comma rule based on clause order, and avoiding the double conjunction error are the habits that make the most difference in accurate, natural writing.