We report on the observation of exclusive decays of B mesons to modes containing a D or D*+ and one or two charged pions. From kinematic reconstruction we determine the masses of the neutral and charged B mesons to be 52126.96.36.199 and 52188.8.131.52 MeV, respectively. The mass difference is 2.01.10.3 MeV. Branching ratios for these modes are given. From the charged-particle momentum spectrum in (4S) decay, we find the average branching fraction for B-meson decay into a D or D* plus a charged pion to be (0.810.16)%. We find no signal for exclusive decays which would arise from the bu transition and set upper limits for several such modes.