1). Because - is a conjunction, used at the beginning of a clause, before a subject and verb. We were late because it rained. I'm happy because I met you. 2). Because of - is a two - word preposition, used before a noun or a pronoun. We were late because of the rain. I'm happy because of you. Note : Because and its clause can go after or before the main clause. I finished early because I worked fast. Because I worked fast, I finished early.