  The purpose of this paper is to study the derived category of simplicial
multicategories with arbitrary sets of objects (also known as, colored operads
in simplicial sets). Our main result is a derived Morita theory for
operads-where we describe the derived mapping spaces between two
multicategories P and Q in terms of the nerve of a certain category of
P-Q-bimodules. As an application, we show that the derived category possesses
internal Hom-objects.
