  We present a supersymmetric model of fermion masses with SU(4)*SU(2)^2*U(1)_X
gauge group with matter in fundamental and antisymmetric tensor representations
only. The up, down, charged lepton and neutrino Yukawa matrices are
distinguished by different Clebsch-Gordan coefficients due to contracting over
SU(4) and SU(2)_R indices. We obtain a hierarchical light neutrino mass
spectrum with bi-large mixing. The condition that anomalies be cancelled by a
Green-Schwarz mechanism leads to fractional U(1)_X charges which exclude $B$
violation through dimension-4 and -5 operators.
