  We propose a novel A4 model in which the Tri-Bimaximal (TB) neutrino mixing
and the charged lepton mass hierarchy are reproduced simultaneously. At leading
order, the residual symmetry of the neutrino sector is Z2 x Z2 which guarantees
the TB mixing without adjusting ad hoc free parameters. In the charged lepton
sector, one of the previous Z2 is maximally broken and the resulting mass
matrix is nearly diagonal and hierarchical. A natural mechanism for the
required vacuum alignment is given with the help of the supersymmetry and an
abelian symmetry factor. In our model, subleading effects which could lead to
appreciable deviations from TB mixing are very restrictive giving rise to
possible next-to-leading predictions. From an explicit example, we show that
our ``constrained'' A4 model is a natural framework, based on symmetry
principle, to incorporate the TB sum rule:
sin^2(\theta_{12})=1/3+2\sqrt{2}(cos(\delta) sin(\theta_{13})/3).
