Coordinating Conjunction Definition and Examples

Is it OK to start a sentence with and?

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A coordinating conjunction is a conjunction (such as and) that joins two similarly constructed and/or syntactically equal words, phrases, or clauses within a sentence, whether they are adjectives, adverbs, nouns, or verbs. It's also called a coordinator.

The coordinating conjunctions in English are and, but, for, nor, or, so, and yet. (See the coordinating conjunction and as it functions in that list of conjunctions?) Compare their use with ​subordinating conjunctions, which join items that are not of equal weight. When joining two independent clauses to create a compound sentence, place a comma before the conjunction. When they join two verbs, for example in the case of a compound predicate, you don't use a comma before the conjunction. ​

Independent Clauses vs. Compound Predicates

Independent clauses look like these examples below. They each have a subject and a verb, making them complete thoughts that stand on their own:

  • She wondered when he would get home. She decided not to call.

If we were to write them as one sentence, we'd either need to join them with a semicolon or a comma and a coordinating conjunction like this: 

  • She wondered when he would get home, but she decided not to call.

Note that each clause keeps its own subject and verb. If they'd be joined without the comma and conjunction, they'd be a fused sentence or a comma splice. 

This version of the sentence contains a compound predicate, two verbs that share the same subject: 

  • She wondered when he would get home but decided not to call.

There's no comma before but because there is only one subject for both verbs. She both wondered and decided. There are no longer two independent clauses. "Decided not to call" can't stand on its own as a sentence.

Conjunctions Starting a Sentence

In some cases, a coordinating conjunction may be used as a transition at the beginning of a new sentence. It can break up a static rhythm between similarly structured sentences or lead off a very short sentence to add emphasis to that sentence in the paragraph. There's some debate whether writers should be able to use the conjunctions in this way or whether that's a rule that shouldn't exist. Author David Crystal explains:

"And at the beginning of a sentence? During the 19th century, some schoolteachers took against the practice of beginning a sentence with a word like but or and, presumably because they noticed the way young children often overused them in their writing. But instead of gently weaning the children away from overuse, they banned the usage altogether! Generations of children were taught they should 'never' begin a sentence with a conjunction. Some still are.
"There was never any authority behind this condemnation. It isn't one of the rules laid down by the first prescriptive grammarians. Indeed, one of those grammarians, Bishop Lowth, uses dozens of examples of sentences beginning with and. And in the 20th century, Henry Fowler, in his famous Dictionary of Modern English Usage, went so far as to call it a 'superstition.' He was right. There are sentences starting with And that date back to Anglo-Saxon times." ("The Story of English in 100 Words." St. Martin's Press, 2012)

Following through with the example in the previous section, it could read like this: "She wondered when he would get home. But she decided not to call." Splitting up the two sentences changes their rhythm and pacing slightly, as compared with having them joined into one sentence with the conjunction between them. Starting a sentence with a conjunction isn't a convention you want to use sentence after sentence, paragraph after paragraph, but it can serve as a tool to create drama in a passage through altering its pacing and rhythm.