In this talk we give an overview of some work on Standard Model extensions, with emphasis on the rôle of symmetries in understanding the masses and mixing in quarks and leptons. In top down models, we explain how the method of reduction of couplings leads to finite theories, which exhibit scale invariance, and point to underlying symmetries at the unification scale, relating the gauge and Yukawa couplings, thus rendering very predictive theories. In the bottom up approach, we follow a phenomenological approach to propose possible flavor symmetries at low energies in multi-Higgs SM extensions, to explain the observed mixing patterns in quarks and leptons. A possible path on how to connect both approaches is then proposed.