  We consider $B^{\pm,0} \to \rho^0(\omega)h^{\pm,0}$, where $\rho^0(\omega)$
decays to $\pi^+\pi^-$ and $h$ is any hadronic final state, such as $\pi$ or
$K$. We find a large direct CP asymmetry in B-meson decays via $\rho \omega$
interference. A possible method to determine weak phases, such as $\phi_{2,3}$,
is discussed. The experimental feasibility is also shown.
