  String theory on D-brane backgrounds is open-closed string theory. Given the
relevance of this fact, we give details and elaborate upon our earlier
construction of oriented open-closed string field theory. In order to
incorporate explicitly closed strings, the classical sector of this theory is
open strings with a homotopy associative A_\infty algebraic structure. We build
a suitable Batalin-Vilkovisky algebra on moduli spaces of bordered Riemann
surfaces, the construction of which involves a few subtleties arising from the
open string punctures and cyclicity conditions. All vertices coupling open and
closed strings through disks are described explicitly. Subalgebras of the
algebra of surfaces with boundaries are used to discuss symmetries of classical
open string theory induced by the closed string sector, and to write classical
open string field theory on general closed string backgrounds. We give a
preliminary analysis of the ghost-dilaton theorem.
