Arranging and Composing?

[Delirium-Zer0]

Not usually, often the singer does the composing, or a songwriter who does nothing but write; but the producer will often decide what composition to use for a song.

The producer basically figures out who's gonna play everything, who should write the melody (in the case of a singer who doesn't write the melody), who's gonna mix it. and they decide the overall sound of a song. They frequently work an album at a time, but not always. Sometimes artists do the production themselves.