The Compound Sentence

 on Connie


Remember the definition of a run-on?  Two sentences combined illegally?

Okay, so how do you combine two sentences legally?  It takes a word -- one word from one of two groups:  coordinating conjunctions, or subordinating conjunctions.

When you use a coordinating conjunction to combine two sentences, the resulting sentence is called a compound sentence.   



Compound Sentence

SV, coor SV.


When I speak of two sentences, we must have two units -- two kisses.  A compound sentence would read like this: 

George went to town, but Mary watched a movie.  Now we have two kisses:  the one  between George and went and the one between Mary and watched.

GeorgeKisswent to town, but MaryKisswatched a movie.

So here's how you punctuate a compound sentence. 

SV, coor SV.  (coor = coordinating conjunction)




Here are some compound sentences:

  • My sonKisswas tired, but heKisswouldn't go to bed.

  • YouKisscan have tuna fish salad, or youKissmight like the chicken sandwich.

  • WeKissran out of money, so weKisscouldn't buy the new DVD.

  • DucklingsKissare soft, yet bunniesKissare softer.

  • The houseKisshad been ransacked, and the carKiss was missing.

Without the markups showing, here are some more compound sentences:

  • I didn't want to hurt his feelings, nor could I stay in the relationship.

  • The chicken is excellent, but the noodles are tough.

  • My dogs were afraid of the lightening, so they hid under the bed.

  • The sun is bright, and the sky seems an eternity away.

  • I cooked a nice meal, yet my husband couldn't eat it.

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More about coordinating conjunctions


These seven words can be used to combine or connect anything -- nouns, adjectives, or whole sentences. George and Mary went to town and watched a movie.   The first "and" is combining two nouns, and the second "and" is combining two verbs.

George went to town, and he watched a movie.  The "and" here is combining two complete sentences.

 When they combine anything less than a sentence, you don't use commas to separate the parts being combined.  Think of it as "ham and . . ."

 Finish this sentence:

I would like ham and . . . . 

Now say the whole sentence aloud.  Say it again, naturally, and notice how the "and" becomes a part of the "ham."  It's more like "ham'n'whatever," isn't it?  The lack of a comma here before the "and" means that a small unit, on the level of the ham, is going to be combined with the ham.  Even if you finished the sentence with an extremely complicated description of a dish never before thought of, it's still on the same grammatical level as "ham."  (I would like ham and onions sautéed in barbecue sauce. = I would like ham'n'onions-sautéed-in-barbecue-sauce.)

 Putting a comma before the "and" indicates that it isn't "ham'n'something" but rather the element being connected to the first sentence is a WHOLE sentence.  Something BIG is coming up; take a deep breath.

  •  I would like ham, and my son would like bacon.

  • I would like ham, and I want it now!

  • I would like ham, and I'll take it to go.

 Even mentally, you would not read that "and" as an "'n'" in these sentence.   I would like ham'n'my son . . . huh?  You'd be giving conflicting signals.



Try turning the following simple sentences, which I call "ham'n'eggs" sentences, into compound sentences.

He returned home from the hunting trip tired but happy.

Neither I nor my dog would eat such food.

My student is either lazy or bored.

Jesse wanted the sandwich with mustard but with no bread.

Henry's sister walks her dog every day and feeds it every other day.

I've got work to do, people to meet, and miles to travel before the end of the day.

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  • for

  • and

  • nor

  • but

  • or

  • yet

  • so

One of the ways to remember the seven coordinating conjunctions (a clever mnemonic) is FANBOYS.  To use the mnemonic correctly, however, you have to memorize which words go with which letters.  (It won't do for you to think the F represents "from" -- which definitely is NOT a coordinating conjunction.)

And one of my problems with the mnemonic is the fact that it begins with "for" -- perhaps the least used of all the coordinating conjunctions. 

 Finish this sentence:

I went to the store for . . .

 Almost everything you think of will use "for" as a preposition.

  • for my mother.

  • for eggs.

  • for eggs for my mother.

  • for eggs to make a big breakfast.

 This is how it's used as a coordinating conjunction.

 I went to the store, for we were out of eggs.

 Sound weird?  Sure.  In fact, we would only use that phrasing if we wanted to make it sound poetic or Shakespearian.  Otherwise, we'll use "because" which isn't even a coordinating conjunction.

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Seeing those commas before the coordinating conjunctions leads people to think that the comma is combining the sentences.  They hardly even noticed the conjunctions.  But here's the deal with commas.

Because their primary (sole) purpose is to separate, commas do not combine. 

In the US, two sentences separated by a comma, but without a conjunction to make the combining legal, is called a "comma splice."  Many American teachers use the comma splice as an indicator of low intelligence and lack of skill.  I've heard of one English teacher within my own community college who grades each essay by the number of comma splices she finds in it.  No comma splices means it gets an A, with one it gets a B, and so on.  (I feel like suggesting to my students that if they end up with this teacher, they just need to write one-sentence essays, thus guaranteeing their A.)

What makes these teachers' attitudes seem quite ridiculous is the fact that in British English, (which is used by a vast majority of the world's English speakers) a comma is sufficient.  We'd need a semi-colon or a period to separate the two units in American English whereas in British English, the comma is just fine. 


British English American English
SV, SV.  = okay SV, SV.  = bad = comma splice
SV; SV.  = okay SV; SV.  = okay
SV.  SV.  = okay SV.  SV.  = okay

For those who deal with American English, the comma between two sentences and without a conjunction is like putting a band-aid on a broken leg.  It's recognizing there's something needed there, but there is not enough solution.

A leg in a cast with a bandaid on the cast

The solution, then, is to add a coordinating conjunction if you really want the two combined (or a subordinating conjunction, which we will get to later.)  Or you may just want to give it up and let the two sentences remain two sentences.  That means using either a semi-colon or a period instead of the comma.

More on the semi-colon

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  This page was last updated Thursday, August 14, 2014, by Connie Gulick.

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