Compound Complex Sentences

Compound complex sentences are the most complicated and difficult sentences to write well.

This is a sentence or statement that contains more than one main clause and has one or more subordinate clauses. So as you may gather, this type of sentence can be very long and elaborate.

Are compound-complex sentences difficult to write?

Well, that depends. I believe these sentences are not too difficult to write, once you understand and are comfortabe with the syntactical terms and rules.

Let's go through those terms together.

Ok, this type of sentence must have two main clauses and also a subordinate clause.

For those of you who are unsure of syntactical terms, a clause is a group of words that contains a subject and predicate. It also, of course, must contain a verb. So, a simple sentence is actually a clause, or main clause.

For instance, 'I looked out the window.' (simple sentence - main clause)

A subordinate clause is a little different to a main clause. A subordinate clause cannot stand alone. It must be linked to a main clause.

For instance, 'As I put my coat on...' (subordinate clause) As we can see, 'as I put my coat on,' is an incomplete sentence or statement.


compound sentence is two main clauses (simple sentences) linked together by a coordinating conjunction. Both main clauses in a compound sentence could stand alone as simple sentences. The coordinating conjunction makes the two independent sentences into one long one.

For example, 'I looked out the window but I couldn't see any rain.' The 'but' is the coordinating conjunction here.

Now, complex sentences can be a little more difficult to grasp. Complex sentences have a single main clause, but also have a subordinate clause attached to the main clause. If we join together our earlier examples, we get...'as I put my coat on, I looked out the window,'

As we learnt earlier, the subordinate clause cannot stand alone and needs the main clause to be considered a complete thought.

A compound complex sentence is simply a complex sentence that has an extra main clause attached to it. The extra main clause is of course attached by a coordinating conjunction, as is the rule for compound sentences.

So to sum up, we have two main clause attached by a coordinating conjunction, and also one or more subordinate clauses.

For example, 'As I put my coat on, I looked out the window, but I couldn't see any rain.'

For a clear definition and example please download this free pdf file.

Compound-Complex Sentence Guide
Right-click to download this PDF file here.


Andrews, R. Torgerson, C. Beverton, S. Freeman, A., Locke, T., Law, G., (2006) The effect of grammar teaching on writing development. British Educational Research Journal, 32, 39-55

Gummersall,D. & Strong, C. (1999) Assessment of complex sentence production in a narrative context. Language, Speech and Hearing Services in Schools, 30 153-164

Merrick, D. (2009) Blake's Grammar Guide for Primary Students. Pascal Press

Content Last Modified 8/11

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