  Exclusive hadronic B-meson decays into two-body final states consisting of a
light pseudoscalar or vector meson along with an eta or eta' meson are of great
phenomenological interest. Their theoretical analysis involves decay mechanisms
that are unique to flavor-singlet states, such as their coupling to gluons or
their ``intrinsic charm'' content. These issues are studied systematically in
the context of QCD factorization and the heavy-quark expansion. Theory can
account for the experimental data on the B->K^{(*)} eta^{(')} branching
fractions, albeit within large uncertainties.
