Because at the Beginning of a SentenceHow to use "because" at the beginning of a sentence correctly
The rule that you can’t begin a sentence with because is pounded into the heads of kids everywhere (at least in the United States), and many of them never get the message that this rule is fallacious. Elementary school teachers teach this rule because they know that most young kids aren’t yet grammatically sophisticated enough to understand how to write such sentences correctly. The rule that many people never properly learn is this: As long as a because clause is followed by an independent clause that explains its outcome or consequences, it is perfectly acceptable.
Because the dog had eaten five pounds of chocolate in ten minutes.
This is unacceptable because it is a fragment. It contains only a dependent clause and does not explain (in an independent clause) what resulted from this action. A sentence that does so is perfectly acceptable:
Because the dog had eaten five pounds of chocolate in ten minutes, it vomited forth a river of black goo.
This sentence shows the cause and the effect. It has an independent clause and expresses a complete thought, so it is a complete sentence.
Although we use such “because” fragments in conversation quite frequently (“Why?” “Because I told you so!”), they should be avoided in writing.
Common Errors in English Usage: Errors in diction and idiom commonly made by native speakers of English
List of Common Errors in English Usage (PDF): Printable version of the complete list
Common Grammar Errors: A list of common errors in grammar (topics like subject-verb agreement and parallelism) as distinct from usage