Core Grammar #4: Compound Sentences

Balanced Sentences

Two independent clauses in one sentence

We saw in The 4 Types of Sentence Structure that a compound sentence is two (or more) independent clauses joined by a coordinating conjunction or semicolon. So a compound sentence is like two or more simple sentences added together. A compound sentence does not contain any dependent clauses.

Joining Compound Sentences with Coordinating Conjunctions

Usually, we join independent clauses with one of the seven coordinating conjunctions.

independent clause coordinating conjunction coordinating conjunction independent clause

The term coordinating conjunction sounds complicated, but in fact there are only seven of them and they are all short, one-syllable words: For—And—Nor—But—Or—Yet—So. Remember them with the mnemonic FANBOYS.

The most common of these coordinating conjunctions are and, but and or, in that order. Note that a comma (,) must come before the coordinating conjunction except when the clauses are short (in which case the comma is optional).

independent clause coordinating conjunction independent clause

Trouble Spot

When you use a coordinating conjunction plus comma to join two independent clauses, the comma ALWAYS comes before the conjunction.

Do not write like this:

Write like this:

The coordinating conjunctions in action

and

The and conjunction is the most common conjunction. It has several uses.

but

We use the but conjunction to introduce a clause that contrasts with the preceding clause, for example: Mary ran fast, but she couldn't catch John.

or

We use the or conjunction to join two alternative clauses, for example: Will Mary go, or will John go?

nor

We use the nor conjunction to join two alternative clauses when the first clause uses a negative such as neither or never. In this case both clauses are untrue or do not happen, for example: Mary never wrote the letter, nor did she call him. (Note the inversion of subject and auxiliary: did she.)

for

We use the for conjunction (meaning something like because) to join two clauses when the second clause is the reason for the first clause, for example: He felt cold, for it was snowing.

yet

The yet conjunction is similar to but. It means something like but at the same time; but nevertheless; but in spite of this. As with but, there is a contrast between the clauses, for example: I have known him for a long time, yet I have never understood him.

so

The so conjunction means something like therefore; and for this reason. We use so to join two clauses when the first clause is the reason for the second clause, for example: He was feeling sick, so he went to the doctor.

Usage notes

  1. Note that when using a coordinating conjunction, you can (if you wish) remove any subject word and modal auxiliary from the second clause. (This is not possible with subordinating conjunctions.)
  2. Another use for nor is in the neither ... nor construction. (Note: When you use neither, you are saying that two items are following.)
  3. A page filled with nothing but balanced compound sentences is as boring as a page filled with nothing but simple sentences, and for much the same reason. Everything weighs the same, so the reader cannot figure out what you want to emphasize. You also need to master complex sentences and compound-complex sentences.

Joining Compound Sentences with Semicolons

Occasionally, we join independent clauses with a semicolon (;).

independent clause coordinating conjunction independent clause

Joining Compound Sentences with Conjunctive Adverbs

We can also join independent clause with words and phrases like moreover, however, at least (conjunctive adverbs). In this case, the conjunctive adverb must be preceded by a semicolon (;) and followed by a comma (,).

independent clause coordinating conjunction conjunctive adverb coordinating conjunction independent clause

Look at these examples:

How to join independent clauses
comma + coordinating conjunction Independent clause

, for

, and

, nor

, but

, or

, yet

, so

independent clause.
semicolon ;
semicolon + conjunctive adverb + comma

; moreover,

; however,

; indeed,

; therefore,

; at least,

Do not try to join independent clauses with a comma alone—that's impossible!

Compound Sentence Examples

Now look at some more examples showing compound sentences and coordinating conjunctions or semicolons in context.

Compound Sentences with Coordinating Conjunctions

English has only seven coordinating conjunctions: for, and, nor, but, or, yet, so. (I always remember them with the acronym FANBOYS.) Notice that you need a comma before the coordinating conjunction.

If you have more than one independent clause, you can use more than one coordinating conjunction:

Compound Sentences with Semicolons

Compound Sentences with Conjunctive Adverbs


This page was adapted from:

"Compound Sentences" EnglishClub: Learn or Teach English, 2018, https://www.englishclub.com/grammar/sentence/compound-sentence.htm. Accessed 29 May 2018.


The views and opinions expressed in this page are strictly those of the page author.

The contents of this page have not been reviewed or approved by Ashland University.

Revised 1/3/22 • Page author: Curtis Allen • e-mail: callen@ashland.edu.