It can be challenging to tell if a dependent clause is noun, relative, or adverb clause. Try identifying the clauses underlined below.
The process through which they do it depends on the software they use.
The analysis by the news channel showed that voter turnout was high in areas where popular leaders of the political party campaigned.
The first has two relative clauses; the second has a noun and a relative clause. We’ll take these examples up again threadbare later in the post.
Once we’ve identified a clause to be dependent, how can we tell if it’s noun, relative, or adverb. We can’t rely on marker words that start the three clauses because some marker words can start more than one dependent clause. For example, when, that, and where can start all three dependent clauses, and who, whose, and whom can start both noun clause and relative clause. Besides, few marker words can play other roles such as determiner, pronoun, and adverb. Therefore, marker words can at best be used to support a finding.
Then what’s the way?
Each clause has few fundamental functions, which are no different from their word counterparts – noun, adjective, and adverb. We’ll largely use their respective functions to identify them.
Let’s go clause-wise. For each clause, we’ll cover few identification tests, which have been ranked on the basis of ease of use. You may, however, choose to pick whichever you want, but try picking more than one test because some tests don’t cover the entire spectrum of their clause and, therefore, may not work in some situations. Moreover, knowing more than one test is a boon because it’ll help you double-check your finding.
Once you get accustomed to the patterns of three clauses, you’ll be able to identify them on the fly without applying any test. At the end of the post, we’ll apply the tests learnt to identify dependent clauses in few sentences.
How to identify a noun clause?
A noun clause is a dependent clause that functions as a noun in a sentence. In other words, it can be the subject, object of verb, object of preposition, subject complement, or object complement in a sentence. Examples:
What you did was beyond our wildest expectations. [Subject]
The police finally found who was behind the crime. [Object of verb]
The captain was undecided on which team to field for today’s match. [Object of preposition]
The answer isn’t what you think. [Subject complement]
We’ll use these examples for the noun clause tests that follow.
Test 1: Is the sentence incomplete after dropping the clause?
If the answer is yes, it’s a noun clause?
Adjectives and adverbs are modifiers. Without them, a sentence can stand perfectly, though with less details. But if a noun is removed from the subject, object of preposition, or subject complement position, the sentence would not make any sense. None of these sentences, for example, can stand if we drop the clause.
What you did was beyond our wildest expectations.
The captain was undecided on which team to field for today’s match.
The answer isn’t what you think.
When you drop a clause that is object of verb, the remaining sentence will still look like a sentence, even though it’s not a sentence from grammatical viewpoint.
The police finally found who was behind the crime.
The expert committee told the government that urgent steps are required to boost the economy.
The verbs found and told require an object, and hence these sentences are incomplete, but it may be challenging for a beginner to tell. Therefore, to keep the test simple, we’ll take only non-sensical sentences, like the three above, as incomplete sentences.
To sum, if dropping the clause results in a non-sensical sentence, the dropped clause is a noun clause. But if the resulting sentence can stand, it could be any of the three dependent clauses, like in these examples.
The expert committee told the government that urgent steps are required to boost the economy.
I’m a living example of the dictum that an hour in the morning is worth two in the evening. [Relative clause]
When I’m not focusing on something, I get lost in thoughts. [Adverb clause]
Test 2: Does the clause follow a verb and/or pose an indirect question?
If yes, it’s a noun clause.
A clause immediately after a verb will most likely be a noun clause functioning as object of the verb. And you can be almost certain if the verb is a reporting verb (a verb that merely reports someone’s work) such as say, tell, mention, believe, reply, ask, know, think, respond, order, admit, deny, and complain. This, in fact, happens to be the most common use of noun clause.
The police finally found who was behind the crime. [Immediately after a verb + indirect question]
We need to rethink how we train our students. [Immediately after a verb + indirect question]
These four charts show who is ahead in the race to best year-end performance. [Immediately after a reporting verb + indirect question]
The newspaper reports that the government is planning a relief package for the industry. [Immediately after a reporting verb]
Note: This is a quick test to tell with very high, but not 100%, certainty that the clause is noun.
An adverb clause too can sometimes follow a verb.
He had left when I reached there.
I’ll not leave unless you agree to approve the project.
But here the clauses aren’t object of the verb. They’re merely stating time and condition, respectively, that govern the main clause.
If a test is not 100% certain, you can use it for a quick conclusion, which can then be confirmed by other tests.
Exception
The clause though may not immediately follow verb if the sentence contains an indirect object. In this sentence, for example, the indirect object the government comes in between the reporting verb told and the clause.
The expert committee told the government that urgent steps are required to boost the economy.
Don’t confuse the above clause with the relative clause. Like the above clause, a relative clause comes immediately after a noun or noun phrase, but the above clause is not a relative clause as it is not describing the government.
Write Sentences Like in Newspapers and Books
Step-by-step process. Little grammar. Real-world examples.
Test 3: Does the clause follow a preposition?
If the answer is yes, it’s a noun clause.
A preposition can be followed only by a noun. Hence, a clause following a preposition will always be a noun clause. In this sentence, for example, the clause follows the preposition on. Hence, it’s a noun clause.
The captain was undecided on which team to field for today’s match.
Test 4: Can the clause be replaced by a noun or pronoun?
If the answer is yes, it’s a noun clause.
Because a noun clause functions like a noun, we should be able to replace it with a noun (including a noun phrase) or pronoun without disturbing the sentence grammatically. Let’s do this in the examples we saw earlier.
It was beyond our wildest expectations.
The police finally found him. [We need an object pronoun him here as it is replacing object of the verb.]
The captain was undecided on it.
The answer isn’t zero. [A noun replacing the clause.]
They all make meaningful sentences. Since the clauses can be replaced by nouns or pronouns, they’re noun clauses.
Test 5: Does the clause answer who, whom, or what in a sentence?
If the answer is yes, it’s a noun clause.
We know that subject of a sentence answers the question who or what, and object of verb or preposition answers the question whom or what. If the dependent clause answers who or what, it’ll be the subject in the sentence, and if it answers whom or what, it’ll be the object of verb or preposition in the sentence. And only a noun clause can be a subject or object.
Note that noun clause occurs mostly in the subject and object positions, and hence this test will cover most, if not all, occurrences of noun clauses. Examples:
What you did was beyond our wildest expectations. [The clause answers what: What was beyond our wildest expectations.]
The police finally found who was behind the crime. [The clause answers whom: The police finally found whom.]
The captain was undecided on which team to field for today’s match. [The clause answers what: The captain was undecided on what.]
Special case of noun clause without a marker word
The marker word that can be left out in noun clauses under certain conditions. Examples:
Scientists believe that Covid is going to stay with us for at least few years.
Before you can decide whether a clause is noun, relative, or adverb, you’ve to first find the dependent clause itself in the sentence, which could be a challenge for some because of absence of a marker word. But once you’ve found the clause, you can apply the above tests to ascertain if it’s a noun clause. (Relative clauses too can come without a marker word.)
You can though bypass above tests in case of dependent clause without marker word. When you see a sentence-like unit (Covid is going to stay with us for at least few years) immediately after a reporting verb (believe, say, tell, mention, know, think, etc.), it’s a noun clause with that dropped.
How to identify a relative (or adjective) clause?
A relative clause is a dependent clause that describes (or modifies) nouns just like an adjective does, but unlike an adjective it almost always follows the noun it describes. Because it functions like an adjective, a relative clause is also called an adjective clause. Examples:
Those who live in a glass house don’t throw stones.
I’m a living example of the dictum that an hour in the morning is worth two in the evening.
Greenhouse gases, which originate mainly from human activities such as transportation, electricity, and industry, are warming our planet to a dangerous level.
I invested in ten different companies, three of which returned losses. [A relative clause is sometimes preceded by a quantifier + of]
It’s difficult to advise a person on a matter in which she is an expert. [A relative clause is sometimes preceded by a preposition]
We’ll use these examples for the relative clause tests that follow.
Test 1: Does the clause describe a noun (or noun phrase) and follows it
If the answer is yes, it’s a relative clause.
In all the examples, the clause describes the noun or noun phrase (in magenta font) and immediately follows it. Hence all the clauses are relative clauses.
Those who live in a glass house don’t throw stones.
I’m a living example of the dictum that an hour in the morning is worth two in the evening.
Greenhouse gases, which originate mainly from human activities such as transportation, electricity, and industry, are warming our planet to a dangerous level.
I invested in ten different companies, three of which returned losses.
It’s difficult to advise a person on a matter in which she is an expert.
So, whenever you see a clause next to a noun or noun phrase, it’s most likely a relative clause. You should then confirm it by seeing if it’s describing the noun.
Test 2: Does the clause begin a sentence?
If the answer is yes, it can’t be a relative clause.
Note: This test can be used to eliminate the option of relative clause.
Unlike an adverb clause or a noun clause, a relative clause can never begin a sentence.
What you did was beyond our wildest expectations. [Noun clause begins a sentence]
Because it was raining outside, I exercised indoors. [Adverb clause begins a sentence]
Special case of relative clause without a marker word
Earlier we saw that marker word that can be left out in noun clauses. Far more marker words (who, whom, which, and that) can be left out in relative clauses. Examples:
Don’t ask questions which people can’t or don’t want to answer.
He is a person whom you can disagree with, and he won’t mind.
She may be assigned the project that she worked on last year.
Once you’ve identified the clause, the above tests apply on them as well.
You can though bypass these tests in case of dependent clause without marker word. When you see a sentence-like unit (people can’t or don’t want to answer) immediately after a noun or noun phrase (questions), it’s a relative clause with its marker word dropped.
Special case of relative clause with marker word which
A relative clause starting with which can function in two ways. Besides describing a noun or noun phrase, it can describe the preceding clause. In the latter function, it’s called sentential relative clause and is always preceded by a comma.
My dog, which is a German Shepherd, likes playing fetch. [Regular relative clause that comes after the noun phrase My dog and describes it]
My dog snarled at me, which came as a surprise to me. [Sentential relative clause. Here, the clause doesn’t describe My dog; it describes My dog snarled at me. After all, the dog didn’t come as a surprise; its snarling did.]
Now, which can start a noun as well as a relative clause. But if you come across a sentential relative clause like which came as a surprise to me, your tests for all three dependent clauses will fail, even though the clause is a relative clause, albeit of a different hue.
So, when you see a clause starting with which that doesn’t seem to fit any pattern, check if it is modifying the preceding clause and has a comma before it.
How to identify an adverb clause?
An adverb clause is a dependent clause that acts as an adverb in a sentence, implying two things. First, it modifies adjectives, verbs, and adverbs (mainly verbs and rarely the other two). Second, it answers adverbial questions such as when, where, why, in what manner, to what degree, and under what condition to provide necessary background information in a sentence. Examples:
Because it was raining, I exercised indoors.
When I’m not focusing on something, I get lost in thoughts.
If you want your children to have a peaceful life, let them suffer a little hunger and a little coldness.
Even though the product wasn’t completely ready, the company decided to launch it.
We’ll use these examples for the adverb clause tests that follow.
Test 1: Can the clause be moved around in the sentence?
If yes, it’s an adverb clause?
Unlike other clauses, adverb clauses can often occupy more than one position in a sentence. So, try moving a clause from the front to the end (and vice versa), and see if the sentence makes sense. If it does, then it’s an adverb clause. All the sentences below make perfect sense, even though the clauses have been moved to the back position. Hence, they’re all adverb clauses.
I exercised indoors because it was raining.
I get lost in thoughts when I’m not focusing on something.
Let your children suffer a little hunger and a little coldness if you want them to have a peaceful life.
The company decided to launch the product, even though it wasn’t completely ready. [Few subordinating conjunctions such as although and even though that express contrast take comma in the back position.]
This test comes quite handy with marker words we’ve no clue start an adverb clause. Example:
By the time the fireman entered the room, it was filled with smoke.
The room was filled with smoke by the time the fireman entered.
This test though wouldn’t work with a tiny fraction of subordinating conjunctions such as as if, as though, in order that, and so that, which can come only after the main clause and hence can’t be moved around. For example, you can’t bring the adverb clause to the front position in these sentences.
Tom works the hardest so that he could rise in the hyper-competitive industry.
You look as though nothing has happened.
The winter chill continued as if it would never end.
Test 2: Does the clause answer adverbial questions?
If the answer is yes, it’s an adverb clause.
If you see the clause answering questions such as when, where, why, in what manner, to what degree, and under what condition, you’ve an adverb clause at hand. These are common adverbial questions, but they don’t constitute an exhaustive list. Examples:
Because it was raining, I exercised indoors. [Answers the adverbial question why]
When I’m not focusing on something, I get lost in thoughts. [Answers the adverbial question when]
If you want your children to have a peaceful life, let them suffer a little hunger and a little coldness. [Answers the adverbial question under what condition]
Even though the product wasn’t completely ready, the company decided to launch it. [Answers the adverbial question how two things contrast with each other]
Test 3: Does the clause modify adjective, verb, or another adverb?
If the answer is yes, it’s an adverb clause.
Identifying the noun being modified by a relative clause isn’t difficult because of physical proximity between the two. But identifying the adjective, verb, or adverb being modified by an adverb clause can be challenging. If you can, then you can use this test to identify adverb clause.
In all the examples we saw earlier, the clause is modifying the verb in the main clause.
Test 4: Is the marker word itself subject or object of the clause?
If the answer is yes, it’s not an adverb clause.
Note: This test can be used to eliminate the option of adverb clause. This test though is tough to apply if you don’t know how to identify subject in a dependent clause.
Like all clauses, an adverb clause too has its own subject and verb. Adverb clause, however, is different from noun clause and relative clause in that its marker word can’t be its subject or object. What does this imply? It implies that in adverb clause you’ll always find the marker word followed by a noun or pronoun functioning as the subject of the clause. In the examples below, note that noun and relative clause may or may not have marker word as its subject.
I don’t know what he is up to. [Noun clause with he as subject of the clause]
I don’t know what transpired in the meeting. [Noun clause with what as subject of the clause]
I lost the watch that you bought last month. [Relative clause with you as subject of the clause]
I lost the watch that hardly worked. [Relative clause with that as subject of the clause]
I went for shopping when I was free. [Adverb clause with I as subject of the clause. There will never be a case in which when or other subordinating conjunction will be the subject or object of the clause.]
So, like in second and fourth examples, whenever you see a clause without a noun or pronoun as its subject – and there are plenty of such clauses – you can rule it out as an adverb clause.
Examples of identifying noun, relative, and adverb clause
In each of the sentences below, we’ll use the tests learnt to identify the type of dependent clause. Since there are multiple tests, there can be multiple ways to arrive at the same result.
1. The man who was behind the crime has been finally found by the police.
You can straightaway see that the clause follows the noun phrase The man and is describing it, indicating that it’s a relative clause. Moreover, who is one of the marker words of relative clauses.
2. The police nabbed the culprit when he was trying to flee.
The marker word when characterizes all three dependent clauses. So, the clause could be any of the three. Here is one approach to identify it.
You can straightaway tell that the clause is answering the adverbial question when in the sentence and hence is an adverb clause. You can confirm it by shifting the clause to the front position, where it sounds logical. Once you get experienced at identifying clauses, you would straightaway, in a blink, identify one or more distinguishing patterns and tell what clause it is.
Alternatively, you can rule out the other two clauses.
Even though the clause is placed next to the noun phrase the culprit, it’s not a relative clause because it is not describing the culprit (who was in grey t-shirt, etc.). It is merely telling the time of his nabbing.
3. The analysis by the news channel showed that voter turnout was high in areas where popular leaders of the political party campaigned.
The clause follows a verb and answers what, indicating that it’s a noun clause.
Now, the noun clause contains another clause, where popular leaders of the political party campaigned. You can straightaway see that the clause follows the noun phrase areas and is modifying it, indicating that it’s a relative clause. Moreover, where is one of the marker words of relative clauses.
4. Health officials have warned the government that its effort to vaccinate six million people a day will face bump as supply of vaccines is yet to catch up.
We looked at a similar example earlier. Here, that clause follows the verb, with an interruption by indirect object the government. Moreover, it answers the question what. Hence, it’s a noun clause. Note that the clause comes after a noun phrase the government, but it’s not a relative clause because it’s not describing the government. It is merely stating the warning from health officials.
The noun clause contains another clause, as supply of vaccines is yet to catch up. It answers the adverbial question why, and it can be moved to the front position: As supply of vaccines is yet to catch up, the government’s effort to vaccinate six million people a day will face challenge. Hence, it’s an adverb clause.
5. The process through which they do it depends on the software they use.
Both the clauses follow noun phrases and describe them. Hence, they’re relative clauses. These are somewhat atypical relative clauses: the first has a preposition through before the marker word, and the second has no marker word.
Alternatively, you can eliminate the option of other two clauses.
6. What you did on the field today was not what we had discussed.
Dropping each clause at a time will result in non-sensical sentences, implying both are noun clauses.
Marker words common to two or more dependent clauses
Some of the marker words are common to two or even all three dependent clauses.

Note: Feel free to use the above image, using the link (url) of this post for reference/attribution.
Understanding how common marker words function differently in different clauses will help you tell the three clauses apart more easily. Here are the examples showing how common marker words are used.
Who
I don’t know who Tom is. [Noun clause]
Tom, who was last seen on Monday, came to college today. [Relative clause]
Whose
I don’t know whose book is this. [Noun clause]
Tom, whose first few books bombed, has written few best sellers. [Relative clause]
Whom
I am undecided about whom should I vote in the coming election. [Noun clause]
These days it’s hard to find a person whom voters have trusted for more than two consecutive elections. [Relative clause]
Which
Straws tell which way the wind is blowing. [Noun clause]
Straws which aren’t bent in any direction indicate absence of wind. [Relative clause]
Straws are bent toward north, which means the wind is blowing in that direction. [Sentential which clause describing the entire preceding clause]
That
That he missed today’s important meeting is bit strange. [Noun clause]
The diary that I left on the table is nowhere to be seen now. [Relative clause]
He works the hardest so that he could rise in the hyper-competitive industry. [Adverb clause. That is used with so to express adverbial meaning of result or consequence of something.]
When
I’m not too concerned about when the exams will be held. [Noun clause]
I can never forget the day when I was not allowed to take the exams because I reached 15 minutes late. [Relative clause]
When I reached the venue, the exam had already started. [Adverb clause]
Where
My friends don’t know where I work out. [Noun clause]
The gym where I work out is closed for renovations. [Relative clause]
I went where I could find the best-equipped gym. [Adverb clause]
Why
I don’t know why so many are running late tonight. [Noun clause]
Could this be the reason why so many are running late tonight? [Relative clause]
Whether
Whether he cheated or not should be investigated impartially. [Noun clause]
Whether I pass or fail, I’ll not cheat. [Adverb clause]
If
I doubt if he’ll come for the meeting. [Noun clause]
You won’t be allowed in if you are late for the meeting even by five minutes. [Adverb clause]