A Guide to Compound-Complex Sentences

In English grammar, a compound-complex sentence is a type of sentence that contains at least three clauses—two independent clauses and one or more dependent clauses—which equates to three sets of subjects and verbs. This type of sentence is a combination of a compound sentence with a complex sentence.

A compound sentence is a sentence in which two or more independent clauses are joined together with a coordinating conjunction, like “for” and “yet,” or a conjunctive adverb, such as “however” and “nevertheless.” A complex sentence is a sentence that has one independent clause and one or more subordinate clauses that modify the main subject or verb of a sentence. Compound-complex sentences will typically be joined together with a coordinating conjunction as you would use in a compound sentence, with the comma placed immediately before the coordinating conjunction.

Compound-complex sentences can clearly convey more information than your standard compound or complex sentence. Here are some examples of compound-complex sentences.

1. 1. “There was heavy traffic in the neighborhood, so I used the GPS to find a quicker route, and was able to get there on time.” In this example, “there was heavy traffic in the neighborhood” and “I used the GPS to find a quicker route” are two independent clauses joined by the coordinating conjunction “so,” and followed by the dependent clause, “and was able to get there on time.”
2. 2. “The cat ran away, but nobody was worried because he was trained to find his home.” In this example, “the cat ran away” and “nobody was worried” are the two independent clauses joined by the coordinating conjunctions “but,” and followed by the subordinate clause “because he was trained to find his home.”
3. 3. “Since she was a vegetarian, she refused to eat the turkey, but she was more than happy to eat the potatoes.” In this example, the dependent clause comes at the beginning of the sentence (“since she was a vegetarian”) and is followed by two independent clauses, “she refused to eat the turkey” and “she was more than happy to eat the potatoes” which are joined by the conjunction “but.”

Structuring your compound-complex sentences properly is imperative to avoid run-on sentences and sentence fragments. Successfully arranging a compound-complex can help you clearly express nuanced thoughts or complicated ideas. Here is a quick guide on how to form a complete sentence in the compound-complex structure.

1. 1. Choose your main clauses. Compound-complex sentence structure always includes two independent clauses. Your independent clauses should contain a subject and a verb phrase, enabling them to stand on their own. “I’m going to the mall” and “I need to grab my wallet” are two examples of simple sentences that are also independent clauses.
2. 2. Choose your dependent clause. Attaching a dependent clause to your sentence turns it from a compound sentence to a compound-complex sentence. Modifying the independent clause “I need to grab my wallet” with the dependent adverbial clause “before I go” will turn one of your clauses into a complex sentence.
3. 3. Join the clauses with a conjunction. Coordinating conjunctions such as “for,” “yet,” “and,” and “but” are the connectors that help link your main clauses together. “I’m going to the mall but I need to grab my wallet before I go.”
4. 4. Add your punctuation. A comma usually precedes the coordinating conjunction. In this case, your coordinating conjunction is “but”, before which you will add a comma to make the final sentence “I’m going to the mall, but I need to grab my wallet before I go.” If the phrase starts with a dependent clause, the comma should come right after your clause.

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