  In theories with three light neutrinos, a complete list of five zeroth-order
textures for lepton mass matrices is found, which naturally yield: m_e =
m_mu=0, m_tau \neq 0, Delta m^2_sun = 0, together with theta_{e tau} = 0,
theta_{mu tau} approx 1. These textures provide suitable starting points for
constructing theories which account for both atmospheric and solar neutrino
fluxes. Using flavor symmetries, two schemes for such lepton masses are found,
and example constructions exhibited.
