  We study the characteristic features of J/Psi suppression by deconfinement. A
first order phase transition leads to an essentially discontinuous onset of
anomalous J/Psi suppression. The different energy densities required for the
dissociation of different charmonium states result in a two-step suppression
pattern, in which first the J/Psi's from chi decays are suppressed and
subsequently the directly produced J/Psi states. Combining both features leads
to a unique form of J/Psi suppression in a deconfining medium.
