Define a Subordinate Clause

A subordinate clause is a dependent clause that adds detail to a sentence but can’t stand alone as a complete thought.

Subordinate clauses pop up in essays, reports, and messages. You write “because I missed the bus” or “when the class ended,” and the reader gets the link between events. These word groups feel like mini-sentences, yet they leave a gap that needs filling. That gap is why you define a subordinate clause as dependent.

This guide gives a clear definition, shows the marker words that signal dependence, and walks you through punctuation choices that keep your sentences clean. You’ll also get short practice sets so the idea sticks after you close the tab.

A clause is a group of words with a subject and a verb. A subordinate clause (also called a dependent clause) still has a subject and verb, but it doesn’t express a complete thought on its own. It needs an independent clause to finish the message.

Here’s a fast test. Read the clause out loud and stop. If it feels unfinished, or if you expect more words to make it complete, you’re holding a subordinate clause.

Independent clause: “I finished my homework.”
Subordinate clause: “because I finished my homework”
Full sentence: “I went outside because I finished my homework.”

Type of subordinate clause	What it adds to the main clause	Sample sentence
Adverb clause of time	When something happens	We started the quiz when the teacher arrived.
Adverb clause of reason	Why something happens	I stayed inside because it was raining.
Adverb clause of condition	What must be true	You can borrow my notes if you return them today.
Adverb clause of time order	What happens before or after	She checked her notes before she answered.
Noun clause	What someone thinks, knows, or says	He believes that practice pays off.
Relative clause	Which person or thing	The book that I borrowed is overdue.
Purpose clause	What someone wants to achieve	They left early so that they could catch the bus.
Place clause	Where something happens	Put your bag where you can see it.

What makes a clause subordinate

A subordinate clause is usually introduced by a marker word that signals dependence. The marker tells the reader how the clause connects to the independent clause: time, reason, condition, place, or description.

Subordinating conjunctions that create adverb clauses

Subordinating conjunctions join a dependent idea to an independent one. Common ones include because, when, after, before, if, unless, since, while, where, so that. These words set up a promise: a complete clause is coming to finish the thought.

A quick check helps here. If the dependent part can move to the front without changing the basic meaning, you’re often working with an adverb clause.

“Because I studied, I passed.”
“I passed because I studied.”

Relative pronouns that create relative clauses

Relative clauses start with a relative pronoun such as who, whom, whose, which, that. They attach to a noun and tell you which one, what kind, or how many.

“Students who arrive early can pick their seats.”
“The laptop that I use has a cracked screen.”

Question words that create noun clauses

Noun clauses can start with words like what, when, where, why, how, who or with that. They act like a noun inside a larger sentence.

“I know what you meant.”
“Tell me where you parked.”

Defining a subordinate clause in real sentences

Worksheets often use short, tidy lines. Real writing can place the dependent part in the middle, tuck it at the end, or stack it near another clause. Still, the same rule holds: if the clause can’t stand alone, it’s subordinate.

Use this method on any sentence:

Find each subject and verb pair.
Read each clause by itself.
Mark the clause that feels unfinished.
Circle the marker word (because, that, who, if, when).

Doing this a few times trains your eye. Those marker words start to stand out, and you’ll spot fragments faster in your own drafts.

Subordinate clause types by job in the sentence

A clause can be classified by what it does inside the sentence. This view helps you choose punctuation and avoid awkward sentences, since each type behaves a bit differently.

Adverb clauses

An adverb clause modifies a verb, adjective, or whole clause. It answers questions like when, why, where, under what condition, or for what purpose.

Time: “I’ll call you when I get home.”
Reason: “We left early because traffic was heavy.”
Condition: “You’ll pass if you finish the review.”
Purpose: “She spoke slowly so that everyone understood.”

Noun clauses

A noun clause can act as a subject, object, or complement. One clue: you can often replace the entire clause with “something” and the sentence still makes sense.

Subject position: “What you wrote surprised me.”
Object position: “I remember where we met.”
After a linking verb: “The issue is that the file won’t open.”

Relative clauses

A relative clause modifies a noun. It narrows which person or thing you mean, or it adds extra detail about a noun that is already clear.

Narrowing: “The students who studied finished early.”
Adding detail: “My phone, which is old, still works.”

Where subordinate clauses fit in a sentence

You can place a subordinate clause at the beginning, middle, or end. Placement changes rhythm and emphasis, and it can also change where you use commas.

Subordinate clause at the beginning

Starting with the dependent part sets the scene first. It works well for time, reason, and condition.

“When the bell rang, we packed up.”
“If you need help, send me your draft.”

Subordinate clause in the middle

Middle placement is common with relative clauses. It adds detail without delaying the main action too long.

“The student who missed class asked for the notes.”

Subordinate clause at the end

End placement lets the main clause land first, then adds the reason, time, or condition.

“We postponed the trip because the roads were icy.”

Punctuation rules that keep subordinate clauses clear

Commas with subordinate clauses follow a simple pattern: opening dependent clauses take a comma; closing ones usually don’t.

Purdue OWL’s comma rules help.

Comma with an opening subordinate clause

When the subordinate clause comes first, use a comma to show where the independent clause begins.

“Because the printer jammed, I emailed the file.”
“After I checked the dates, I booked the room.”

No comma with a closing subordinate clause

When the subordinate clause comes last, skip the comma in most cases.

“I emailed the file because the printer jammed.”
“I booked the room after I checked the dates.”

Relative clauses and commas

Relative clauses fall into two groups. A restrictive relative clause is needed to identify the noun, so it usually has no commas. A nonrestrictive relative clause adds extra detail about a noun that is already clear, so it usually takes commas.

Restrictive: “Students who submit late lose points.”
Nonrestrictive: “My sister, who lives in Oslo, visits in July.”

Situation	Comma needed?	Model sentence
Dependent clause first	Yes	If you’re ready, we’ll start.
Dependent clause last	No	We’ll start if you’re ready.
Restrictive relative clause	No	The people who arrived early got seats.
Nonrestrictive relative clause	Yes	My uncle, who teaches math, loves puzzles.
Two dependent clauses up front	Yes	When the sun set and when the wind rose, we went inside.
Dependent clause interrupting a main clause	Often	The plan, because it saved time, won approval.
Short adverb clause after main clause	No	Text me when you arrive.
Long trailing adverb clause	Usually no	I stayed home because the storm kept growing all evening.

How to shorten subordinate clauses without losing meaning

Reduce a time clause with an -ing phrase

When two actions share the same subject, you can sometimes turn a time clause into an -ing phrase.

Full: “When I opened the app, I saw the update.”
Reduced: “Opening the app, I saw the update.”

Reduce a purpose clause with an infinitive

A purpose clause with “so that” can sometimes become an infinitive phrase.

Full: “I saved the file twice so that I wouldn’t lose it.”
Reduced: “I saved the file twice to avoid losing it.”

Common mix-ups and clean fixes

Most mistakes happen when a subordinate clause is treated like a complete sentence. The fix is simple: attach it to an independent clause, or rewrite it as an independent clause by removing the marker word.

Fragment sentences

Fragments happen when you write only the dependent part.

Fragment: “Because I forgot the charger.”
Fix: “I couldn’t use my laptop because I forgot the charger.”
Rewrite: “I forgot the charger.”

Run-ons that hide the relationship

If you jam two independent clauses together, the reader has to guess the connection. Turning one idea into a subordinate clause can show that link clearly.

Run-on: “I wanted to leave I had no ride.”
Rewrite: “I stayed because I had no ride.”

Too many clauses in one sentence

Subordinate clauses help, yet stacking three or four of them can slow a paragraph down. If a sentence feels heavy, split it into two sentences and keep one dependent clause where it adds the most clarity.

Practice that makes the rule stick

Read each line. Find the clause that can’t stand alone. Then rewrite the sentence so it reads as one complete thought. If you’re stuck, start by writing the independent clause, then attach the dependent one.

Spot the subordinate clause

Because the bus was late, I missed the first question.
The coach who yelled the loudest also smiled the most.
I wonder where the keys went.
We’ll start when everyone is seated.
She packed snacks so that the kids stayed calm.

Rewrite the fragments

When the meeting ended.
That you called me.
Unless the file opens.

Checklist you can use while editing

This quick list helps you proofread drafts and keep subordinate clauses doing their job.

Every sentence includes at least one independent clause.
Any clause starting with because, if, when, while, unless, since, after, before, where, or so that is attached to a main clause.
Opening subordinate clauses end with a comma before the independent clause begins.
Closing subordinate clauses usually skip the comma.
Restrictive relative clauses usually have no commas; nonrestrictive relative clauses usually have commas.
If a sentence feels slow, cut one dependent clause or split the sentence.
If you need emphasis, place the independent clause first, then add the subordinate clause as added detail.

If you ever need to define a subordinate clause on a test, keep it tight: “It has a subject and a verb, but it depends on a main clause to complete the thought.”