Subordinate Clauses Simplified
Including how to punctuate them correctly in your writing
I don’t exactly love parts of speech. Rather than dig in and learn the nuts and bolts of the English language growing up, I’m pretty sure I just learned what I needed and focused instead on the fun of actually writing.
Like many things, though, parts of speech start to make sense once you’ve dived in and analyzed what they’re all about. Take subordinate clauses, for example. The term itself sounds intimidating at first, even to many writers—probably because it sounds like something a writer ought to understand.
The “clause” part is easy enough as it indicates we’re talking about a group of words as in a phrase (except a clause always contains a verb). And “subordinate,” while multisyllabic, is understood as meaning something that might be less important than something else or answers to something else.
Put those two seemingly innocent words together, though, and you have a term that doesn’t exactly sound like a good time. Turns out a subordinate clause can actually be considered a somewhat melancholy part of speech—a tactic that helps me remember what it is—because it can’t stand on its own. Also known as a dependent clause for this reason, a subordinate clause is usually accompanied by a main clause (aka an independent clause because it can stand on its own).
Examples and punctuation
When a subordinate clause is placed in the middle of a sentence, it’s framed by two commas as in, “Their son’s car, which was bought used, has lots of miles on it.” Or those two commas can be replaced by parentheses. Easy-peasy.
Now consider this sentence: “As soon as it was light, they ran outside to play.” Within this sentence is the simple statement “They ran outside to play.” Since that clause can stand on its own, it’s the main clause of the longer sentence. “As soon as it was light,” however, can’t stand on its own because it’s a fragment, making it a subordinate clause.
As in the second example above, a subordinate clause can begin a sentence, but it can also end a sentence. Consider this statement: “They played outside until the streetlights came on.” In it, the subordinate clause, “until the streetlights came on” follows the main clause.
But wait, there’s more. You’ll note there’s no need for a comma in that sentence—and this also would be the case if we were to turn around our second example above and write, “They ran outside to play as soon as it was light.” While there are exceptions (see below), when a subordinate clause follows a main clause, no comma is usually needed.
Types of subordinate clauses
If you really want to get under the hood of subordinate clauses, you might like to know there are three types: noun clauses, adjective clauses, and adverb clauses. Consider the statement: “You are what you eat.” In this example, “what you eat” is a subordinate clause that’s acting like a noun, making it a noun clause.
Consider this statement: “The child laughed at the seals, who were playing in the water.” In this example, “who were playing in the water” is an adjective clause because it modifies something (the seals) just as an adjective would. It also provides extra information that’s not critical to the meaning of the sentence, so it could be set off with parentheses. This is the simplest way I know to identify when a subordinate clause at the end of a sentence should be preceded by a comma. If the info is parenthetical, a comma is in fact needed.
But what if the child was watching an extended family of seals but was only laughing at a few seals playing in some water? In that case, the information provided by the subordinate clause “who were playing in the water” is actually essential to the meaning of the sentence. And in that case, once again, so comma would be needed: “The child laughed at the seals who were playing in the water.”
And now reconsider our original example above: “As soon as it was light, they ran outside to play.” In this sentence, “As soon as it was light” is an adverb clause because it modifies a verb (ran) just as an adverb would.
I find adverb clauses the most interesting of the three because they provide specific details related to an action. Such details can cover when something occurred/is occurring/will occur (as in “as soon as it was light”), why something occurred/is occurring/will occur (as in “because she was tired”), under what conditions something occurred/is occurring/will occur (as in “if the price is right”), and even despite what something occurred/is occurring/will occur (as in “Even though he wanted to skip class”).
While all that is interesting (to me at least!), when it comes to subordinate clauses, I’d argue the most important thing to keep in mind is this: When a subordinate clause begins a sentence, it should always be followed by a comma, but a comma isn’t always needed when a subordinate clause ends a sentence.
Despite how tempting it might be to put a comma before a subordinate clause at the end of sentence when the clause starts with a word like “as,” “unless,” or “until,” it’s usually not needed—and your comma will likely be deleted if the sentence is reviewed by an editor. To remember this, consider what’s wrong with this sentence: “Your comma will likely be deleted, if the sentence is reviewed by an editor.” Exactly.
Key takeaways
While a subordinate (dependent) clause includes a verb, it can’t stand on its own. It needs a main (independent) clause to complete a thought.
When a subordinate clause opens a sentence, it should be followed by a comma.
A comma is generally not needed when a subordinate clause closes a sentence.
There are three types of subordinate clauses: noun clauses, adjective clauses, and adverb clauses.
When a subordinate clause that ends a sentence provides parenthetical information, a comma should precede it.
An earlier version of this post was published in The Writing Cooperative.
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I write fiction, poetry, and nonfiction when I’m not working as a copy editor. Author of the novel One Sister’s Song and the e-book Not Nearly Everything You Need to Know About Writing.