Let R be a commutative ring with identity. An module (ideal of R) A is call
ed a multi plication module (ideal) if for each submodule N of A there exis
ts an ideal I of R with N = IA. We give several characterizations of multip
lication modules. Using the method of idealization we show how to reduce qu
estions concerning multiplication modules to multiplication ideals. For exa
mple, we show that if S is a commutative R-algebra and psi: M --> N an R-mo
dule homomorphism where M is a multiplication R-module and N is an S-module
, then S psi(M) is a multiplication S-module.