$b \to c$ Hadronic Decays

A review of current experimental results on exclusive hadronic decays of bottom mesons to a single or double charmed final state is presented. We concentrate on branching fraction measurements conducted at $e^+e^-$ colliders at the $\Upsilon(4s)$ and at the $Z^0$ resonance. The experimental results reported are then used in tests of theoretical model predictions, the determination of the QCD parameters $a_1$ and $a_2/a_1$ and tests of factorization