  We show that, even in purely soft processes, the hadronic multiplicity in
nucleus-nucleus interactions contains a term that scales with the number of
binary collisions. In the absence of shadowing corrections, this term dominates
at mid rapidities and high energies. Shadowing corrections are calculated as a
function of impact parameter and the centrality dependence of mid-rapidity
multiplicities is determined. The multiplicity per participant increases with
centrality with a rate that increases between SPS and RHIC energies, in
agreement with experiment.
