  Status of nonfactorizable effects in hadronic charmless B decays is reviewed.
Implications of new CLEO measurements on $B^0\to\pi^+\pi^-$ and $B\to\eta' K$
are discussed. Nonfactorizable effects due to color ocet 4-quark operators are
calculated using renormalization group improved QCD sum rules. The resultant
B-meson lifetime ratio $\tau(B^-)/\tau(B_d)$ agrees with experiment.
