Can you start a sentence with because?

A frequently asked question from my grammar classes is this one: Can you start a sentence with because? The short answer is, yes, if you make sure it is in fact a complete sentence. The longer answer is not an answer, but a question: where did you get the idea that you could not?

First, the short answer. You can start a sentence with because, as long as you make sure to fully complete the sentence. One clause beginning with the word because does not constitute a sentence. These are fragments:

*Because the newspapers reported it.*
*Because the river ran dry.*

If you follow the clause beginning with because with a complete independent clause, however, you are in business. These are complete sentences:

Because the newspapers reported it, the neighbors believed it.
Because the river ran dry, the dam would no longer provide electricity.

Now, the long answer. My theory as to why so many people think you cannot start a sentence with because is that school teachers use this “rule” to help students avoid writing fragments like the ones in asterisks above. You may find this rule useful yourself if you are prone to this error. Thus, if you do not allow yourself to start a sentence with because, you will automatically correct fragments beginning with because.

You might correct this fragment:

*Because I said so.*

By creating this complete sentence:

The children stayed inside this afternoon because I said so.

You may also correct fragments like the ones in asterisks above by rewriting so that because is not at the beginning:

The neighbors believed the story because the newspaper reported it.
The dam would no longer provide electricity because the river ran dry.

*Asterisks indicate a grammatically incorrect sentence.