  The NA50 Collaboration has recently observed a strong suppression of J/Psi
production in Pb-Pb collisions at 158 Gev/n. We show that this recent
observation finds a quantitative explanation in a model which relates the
suppression mechanism to the local energy density, whose value is higher in
Pb-Pb collisions than in any other system studied previously. The sensitivity
of the phenomenon to small changes in the energy density could be suggestive of
quark-gluon plasma formation.
