  With the inclusion of nonfactorized amplitudes in a scheme with $N_c=3$, we
have studied Cabibbo-favored decays of $D^0$ and $D^+$ into two-body hadronic
states involving two isospins in the final state. We have shown that it is
possible to understand the measured branching ratios and determined the sizes
and signs of nonfactorized amplitudes required.
