[en] Recent progress on non-linear unitary field theories of elementary particles is reviewed. A simple model of coupled field fits the lepton family well and predicts a particle size within experimental bounds. The role of gravitation in elementary particle formation is explored and it is shown that gravitation is significant only for particles which have e²∼m², unlike the particles with which we are familiar. The phenomenon of Reissner-Nordstrom repulsion is shown to be realized in particles such as the electron. The spatial components of the four-vector potential of electromagnetism can create spin and magnetic moment in analogy with the time component which creates mass and charge. (author)