A general method to derive horizontal symmetry from a mixing matrix is
reviewed. The technique has been applied to deduce leptonic symmetry from the
tri-bimaximal neutrino mixing matrix and three of its variations. The question
of how the quark mixing can be accommodated within the leptonic symmetry group
is discussed, including in this connection an example based on the group D4​.Comment: Luxor09 talk, 7 page