Sometimes you will need to express a complex combination of ideas. A compound-complex sentence includes at least two independent clauses and at least one dependent clause. In other words, it uses both compound and complex sentence structures together to express one big idea.

This type of sentence should be used carefully. Because this type of sentence includes multiple clauses, it requires the most control over grammar accuracy. For example, pronouns in a compound-complex sentence can be unclear. Overuse of the compound-complex sentence type will also make it difficult for your reader to follow your ideas. This is not to suggest that you avoid the sentence structure all together. You just want to be intentional in the way you use them.

• Dr. Castro, whose research is widely cited, is the plenary speaker for the conference, and he will be speaking about advances in genetic testing.
• Although the textbook explains the concept clearly, I would like to see more examples, so I asked the professor some questions.
• Amy will do an internship next semester, or she will study abroad because she wants a wider range of experiences before graduation.

There are many different ways to construct a compound-complex sentence. Here we only give examples of two independent clauses combined with one dependent, but it is possible to create other patterns.

Look for other examples as you read. And always remmeber to consider your audience and purpose when you decide whcih sentence types to employ in your writing.