Abstract1,5‐Diamino‐2,4‐ethylenehexamethyltrisilazane and related compounds were prepared by treating the corresponding chlorosilane intermediates with ammonia or an amine. When these monomers were heated in xylene solution at 140°C. in the presence of ammonium sulfate, linear silicon‐nitrogen polymers were obtained with molecular weights in the range of 7,500–15,000. Elemental analyses, infrared spectra, and the physical properties of the polymers support the proposed structure and polymeriza