We have used the CLEO Pi detector to study the multiplicity of charged part
icles in the decays of B mesons produced at the Y(4S) resonance. Using a sa
mple of 1.5x10(6) B meson pairs, we find the mean inclusive charged particl
e multiplicity to be 10.71+/-0.02(-0.15)(+0.21) for the decay of the pair.
This corresponds to a mean multiplicity of 5.36+/-0.01(-0.08)(+0.11) for a
single B meson. Using the same data sample, we have also extracted the mean
multiplicities in semileptonic and nonleptonic decays. We measure a mean o
f 7.82+/-0.05(-0.19)(+0.21) charged particles per BE decay when both mesons
decay semileptonically. When neither B mason decays semileptonically, we m
easure a mean charged particle multiplicity of 11.62+/-0.04(-0.18)(+0.24) p
er B (B) over bar pair.