Dependent Clauses: Types, Rules and Examples

Overview

A dependent clause, also called a subordinate clause, is a clause that contains a subject and a finite verb but cannot stand alone as a complete sentence. Something in its structure signals incompleteness: usually a subordinating conjunction or a relative pronoun at the beginning that links the clause to a main clause and makes the whole thought dependent on it. Remove the main clause, and the dependent clause becomes a fragment.

The main clause carries the central idea. The subordinate clause supports it, adding detail about time, reason, condition, contrast, identity, or content. That supporting role always requires the main clause to anchor it.

Dependent clauses appear in three grammatical roles. A noun clause acts as a noun: it can be the subject or the object of the main verb. An adjective clause describes a noun in the main clause. An adverb clause modifies the verb or the whole main clause, expressing relationships such as time, cause, and condition.

What Makes a Clause Dependent

A dependent clause becomes dependent because of the word that introduces it. Subordinating conjunctions such as because, although, when, if, since, after, and unless signal that the clause they introduce is subordinate to another. Relative pronouns such as who, which, and that do the same for adjective clauses. Noun clause markers such as that, whether, what, how, and why introduce clauses that function as nouns.

In each case, the dependent clause has its own subject and finite verb. The introducing word is what makes it dependent.

The Three Types of Dependent Clause

Noun Clauses

A noun clause performs the same grammatical roles that a noun or noun phrase performs. It can be the subject of the sentence, the object of a verb, the object of a preposition, or a subject complement. Noun clauses are introduced by words such as that, what, whether, who, how, why, and when.

Noun clauses introduced by that are particularly common after reporting verbs such as say, think, believe, know, confirm, and suggest. In informal English, that is sometimes omitted, but in formal writing, including it improves clarity.

Adjective Clauses

An adjective clause, also called a relative clause, modifies a noun in the main clause. It follows directly after the noun it describes and is introduced by a relative pronoun: who for people, which for things, and that for either. The relative pronoun whose indicates possession, and where and when can introduce adjective clauses that describe places and times.

Adjective clauses divide into two types based on whether their information is essential to identifying the noun or merely additional. Defining relative clauses provide essential information: without them, the identity of the noun is unclear. Non-defining relative clauses add extra information about a noun that is already clearly identified. Non-defining clauses are separated from the rest of the sentence by commas; defining clauses are not.

Adverb Clauses

An adverb clause modifies the verb in the main clause or the entire main clause. It answers questions such as when, why, how, under what condition, and in spite of what. Adverb clauses are introduced by subordinating conjunctions, each of which signals a specific type of relationship.

An adverb clause can appear before or after the main clause. When it comes before the main clause, a comma separates the two. When it comes after, no comma is normally needed.

Dependent Clauses vs. Independent Clauses

A dependent clause becomes an independent clause the moment the subordinating word is removed and the thought becomes complete on its own.

Common Mistakes to Avoid

Mistake 1: Writing a Dependent Clause as a Complete Sentence

A subordinate clause punctuated as a standalone sentence is a fragment. The subordinating conjunction signals that another clause must follow.

Mistake 2: Using That for Non-Defining Relative Clauses

That is used in defining relative clauses. Non-defining relative clauses require which for things and who for people.

Mistake 3: Omitting the Comma After a Fronted Adverb Clause

When an adverb clause comes before the main clause, a comma must separate them.

Mistake 4: Using Both Although and But in the Same Sentence

Although introduces a dependent clause. But joins two independent clauses. Using both in the same construction doubles the connector and produces a grammatical error.

Mistake 5: Confusing Since as Time vs. Reason

Since can introduce either a time clause or a reason clause. When the meaning is reason, because is the clearer and safer choice.

Practice Exercises

Exercise 1: Identify the Type of Dependent Clause

Label each underlined dependent clause as a noun clause (NC), adjective clause (AC), or adverb clause (AdC).

1. She confirmed that the package had arrived.
2. The analyst who wrote the summary presented the findings.
3. Because the results were inconclusive, the study was extended.
4. Everyone knows how the system works.
5. The building where the conference is held is accessible by train.
6. Unless you register by Friday, your place will not be reserved.

Exercise 2: Complete the Sentence

Add an appropriate subordinating conjunction or relative pronoun to complete each sentence. Use each word only once: although, because, that, who, when, if.

1. ______ the manager approved the plan, the rollout began immediately.
2. The intern ______ joined last month has already contributed significantly.
3. She was disappointed ______ the application was rejected.
4. ______ the schedule is tight, the team remains confident.
5. He will present the findings ______ the board is available.
6. The report confirmed ______ further testing was required.

Exercise 3: Correct the Error

Each sentence contains one error related to dependent clauses. Rewrite the sentence correctly.

1. Although the system worked well. There were a few minor issues.
2. The final report, that was submitted on Friday, has been approved.
3. Because the data was incomplete, but the team continued the analysis.
4. Since he started the role he has restructured the entire department.
5. She asked whether the deadline could extended.

Summary

The key is always to attach dependent clauses correctly to a main clause, use the right introducing word for the type of clause, and never let a subordinate clause stand alone as a sentence.