  We consider the coupling of quintessence to observable matter in supergravity
and study the dynamics of both supersymmetry breaking and quintessence in this
context. We investigate how the quintessence potential is modified by
supersymmetry breaking and analyse the structure of the soft supersymmetry
breaking terms. We pay attention to their dependence on the quintessence field
and to the electroweak symmetry breaking, ie the pattern of fermion masses at
low energy within the Minimal Supersymmetric Standard Model (MSSM) coupled to
quintessence. In particular, we compute explicitly how the fermion masses
generated through the Higgs mechanism depend on the quintessence field for a
general model of quintessence. Fifth force and equivalence principle violations
are potentially present as the vacuum expectation values of the Higgs bosons
become quintessence field dependent. We emphasize that equivalence principle
violations are a generic consequence of the fact that, in the MSSM, the
fermions couple differently to the two Higgs doublets. Finally, we also discuss
how the scaling of the cold dark and baryonic matter energy density is modified
and comment on the possible variation of the gauge coupling constants, among
which is the fine structure constant, and of the proton-electron mass ratio
