  We propose a theory to describe fermion mixing. The theory respects the
maximal abelian family symmetries which are spontaneously broken down at a
large scale. We find that quark mixing can be well described in this theory.
Some concrete models are constructed. The crucial point for model building is
to introduce some new particles which are SU(2) gauge singlets and carry -1/3
electric charge. The approximate family symmetries in our low energy effective
theory are naturally achieved. Some interesting phenomena in the effective
theory, especially with two Higgs-doublets, are discussed.
