MASS MATRIX MODELS

It is possible that the hierarchy in the masses and mixing of quarks i s a result of a horizontal symmetry. The smallness of various paramete rs is related to their suppression by high powers of a scale of new ph ysics. We analyze in detail the structure of such symmetries in view o f new experimental data and present explicit models consistent with al l phenomenological constraints. We show that it is possible that the f lavor dynamics can be at accessible energies - as low as a TeV.