Dependent Clause

A dependent clause supports the main clause in a sentence by functioning as an adverb, an adjective, or a noun.

Dependent Adverbial Clause

• He literally stitched mail sacks until his fingers bled . (The dependent clause until his fingers bled modifies the verb to stitch. It is an adverbial clause.)

Dependent Adjective Clause

• The car that your wife sold me last week has broken down. (The dependent clause that your wife sold me last week describes the car. It is an adjective clause.)

Dependent Noun Clause

• Whoever turned the ovens off is keeping quiet. (The dependent clause Whoever turned the ovens off is the subject of this sentence. It is a noun clause.)

The Link between a Dependent Clause and an Independent Clause

• He literally stitched mail sacks until his fingers bled . (subordinating conjunction in bold)
• The car which your wife sold me last week has broken down. (relative pronoun in bold)

Subordinating Conjunctions and Relative Pronouns Used with Dependent Clauses

• after, although, as, because, before, even if, even though, if, provided, rather than, since, so that, than, though, unless, until, whether, while

• how, that, what, when, where, which, who, whom, whose, why

• whoever (who + ever)
• whosever (whose + ever) (Spelling rule: Don't allow ee.)
• whosoever (who + soever)
• whosesoever (whose + soever)

Why Dependent Clauses Are Important

(Issue 1) Using a comma with a dependent clause

Writers are often unsure whether to offset dependent clauses with commas.

Here are the rules:

(Rule 1) If your dependent clause is a fronted adverb, offset it with a comma.

A dependent clause that starts with a subordinating conjunction (e.g., "when," "unless," "because," "until") will be functioning as an adverb. When the clause is positioned at start of the sentence, offset it with a comma. If it ends the sentence, do not use a comma. In these examples, the dependent clauses are shaded and the subordinating conjunctions are bold.

• When the egg whites have the consistency of shaving foam , stop whipping and add the vanilla essence. (The dependent clause is at the start, so a comma is needed.)
• Stop whipping and add the vanilla essence when the egg whites have the consistency of shaving foam . (The dependent clause is at the end, so a comma is not needed.)

For example (adverbial phrases in bold):

• At the stroke of midnight, the carriage will turn back into a pumpkin.
• The carriage will turn back into a pumpkin at the stroke of midnight.

(Rule 2) If your dependent clause is a nonessential adjective, offset it with a comma (or two commas if it's mid-sentence).

When the dependent clause starts with a relative pronoun (e.g., "which," "who," "that"), it will be functioning as an adjective. Do not use a comma before your relative pronoun if the clause is essential for meaning (called a restrictive clause). But, use a comma if the clause is just additional information (called a non-restrictive clause).

For example:

• My auntie who lives in Australia was bitten by a snake. (From this we can infer that there is at least one other auntie who doesn't live in Australia. The clause is essential for meaning. It identifies what it modifies, i.e., it specifies which auntie. This is an example of a restrictive clause.)
• My auntie Sally, who lives in Australia , was bitten by a snake. (This time, the clause is just additional information. It needs commas. This is an example of a non-restrictive clause.)

Top Tip

If you'd happily put parentheses () around your clause, it needs commas.

(Commas, after all, are just a type of parenthetical punctuation.)

(Issue 2) Don't start a declarative sentence with "which."

You cannot start a declarative sentence (i.e. a statement) with "who" or "which." For example:

• I hate mowing the grass. Which isn't good because I have a huge lawn.

Key Points

• If your dependent clause is a fronted adverb, offset it with a comma.
  • Until the bleeding stops , keep applying pressure to the wound.
• If your dependent clause is at the back, don't use a comma.
  • Keep applying pressure to the wound until the bleeding stops .
• If your dependent clause is an essential adjective, don't use commas.
  • The boy who stole your bike wants to borrow our pump. (The clause "who stole your bike" identifies the boy. The clause is essential. That's why it is not offset with commas.)
• If your dependent clause is a nonessential adjective, use commas.
  • Jack Johnson, who stole your bike , wants to borrow our pump. (This time, "who stole your bike" does not identify the person (we know it's Jack Johnson). The clause is non-essential. It's just additional information. That's why it is offset with commas. We could also have used parentheses () or dashes or even deleted the clause.)
• Don't start a sentence with "which" unless it's a question.

This page was written by Craig Shrives.