Definition: A subordinating conjunction joins two clauses by making one clause subordinate to, or dependent on, the other. It makes a stronger connection than a coordinating conjunction does. The subordinating conjunction shows a relationship between the two clauses. Some subordinating conjunctions are made up of more than one word.
Independent: It is raining hard.
Independent: We might get wet.
Loose connection with coordinating conjunction: It is raining hard, and we might get wet. (The reader isn’t told that the reason they might get wet is the rain.)
Stronger connection with subordinating conjunction: We might get wet because it is raining hard. Because it is raining hard, we might get wet. (The reader can see the cause and effect relationship)
Some common subordinating conjunctions
as far as
as long as
as soon as
in order that
so long as
Beware: This is not a complete list, and all of these words are not always used this way. Memorizing the list is not useful. Analyzing how words work together in a sentence is the best way to find them.
Subordinating conjunctions introduce adverb or noun clauses. Adverb clauses tell how, why, to what extent, and under what conditions something happened.
Punctuating subordinating conjunctions
If the subordinating conjunction is between the independent clause and the dependent clause, it is strong enough to hold the sentences together without a comma. (Subordinating conjunctions are superglue! Coordinating conjunctions are just classroom glue.)
You must finish your painting before it dries.
If the subordinating conjunction is at the beginning of the sentence (making the dependent clause an introductory dependent clause), the sentence needs a comma between the two clauses. (If the glue is at the beginning, how is it going to hold anything together? The comma is the glue.)
Before it dries, you must finish your painting.
If the subordinating conjunction is combining two words or phrases, it isn’t acting as a subordinating conjunction. It might be acting as a preposition or adverb. You will need to decide on its punctuation based on that use.
My movie will end before yours.
Note: Many students believe it is incorrect to start a sentence with because. This is because too many students for too many years answer questions with only the second, dependent clause. Teachers want to discourage that, so they tell students that they are not allowed to start sentences with because.
Why did the Chinese build the Great Wall?
Incorrect: Because they were trying to keep out their enemies.
Correct: The Chinese built the Great Wall because they were trying to keep out their enemies.
Correct: Because they were trying to keep out their enemies, the Chinese built the Great Wall.