  We discuss the constraints from rare B and K decays on the Electroweak
Symmetry Breaking (EWSB) sector, as well as on theories of fermion masses. We
focus on models involving new strong dynamics and show that transitions
involving Flavor Changing Neutral Currents (FCNC) play an important role in
disentangling the physics in these scenarios. In a model-independent approach
to the EWSB sector, the information from rare decays is complementary to
precision electroweak observables in bounding the contributions to the
effective lagrangian. We compare the pattern of deviations from the standard
model that results from these sources, with the deviations associated with the
mechanism for generating fermion masses.
