  Exclusive non-leptonic two-body decays are discussed on the basis of a
generalized factorization approach which also includes non-factorizeable
contributions. Numerous decay processes can be described satisfactorily. The
success of the method makes possible the determination of decay constants from
non-leptonic decays. In particular, we obtain f_{D_s}=(234+-25) MeV and
f_{D^*_s}=(271+-33) MeV. The observed constructive and destructive interference
pattern in charged B- and D-decays, respectively, can be understood in terms of
the different alpha_s-values governing the interaction among the quarks. The
running of alpha_s is also the cause of the observed strong increase of the
amplitude of lowest isospin when going to low energy transitions.
