Yes, you can start a sentence with “because.” The confusion likely comes into play from the tendency to create sentence fragments when a sentence starts with “because.” Some style guides prefer that certain conjunctions do not start sentences, such as “and” or “but.” It is also frowned upon to use coordinating conjunctions to start sentences unless you are aiming for a certain effect.
“Because” is a subordinate conjunction however, and as such, it can start a sentence as long as the dependent clause that contains it is followed or preceded by a main, or independent, clause. Many teachers also create the mistaken belief that “because” cannot start a sentence, probably to help students avoid writing sentence fragments.
“Because” is often used at the beginning of dependent (subordinate) clauses. When this holds true, the main clause (independent clause) follows the dependent one, with a comma separating them. The main clause can start or end the sentence when a dependent clause is included in the sentence. Never place a comma after “because.” Consider the following examples:
Example 1 (Incorrect): Because she went to the dance (sentence fragment).
Example 1 (Correct):Because she went to the dance, she was not allowed to go out the following night.
Example 1 (Correct)She was not allowed to go out the following night because she went to the dance.
Example 2 (Incorrect): Because the U.S. presidential elections are in November (sentence
Example 2 (Correct): Because the U.S. presidential elections are in November, TV programming is often increasingly full of campaign ads until after the election.
Example 2 (Correct): TV programming is often increasingly full of campaign ads until after the election because the U.S. presidential elections are in November.
Sometimes starting a sentence with “because” can create a stronger effect on your readers than putting the dependent clause after the main one. Consider the below example:
Example: Because the changes to spending were not drastic enough, the budget is
Example: The budget is ineffectual because the changes to spending were not drastic enough.
Both sentences above are grammatically correct. However, the cause-effect relationship, and its effect on your readers, is stronger when the cause is stated first.