The dispersion of an efficient secondary chromophore into in situ crosslinked nonlinear optical polymer networks is described. The secondary chromophore leads to both enhanced electro-optical (EO) activity (> 260 pm V–1 at 1.31 μm) and alignment stability at 85 °C. Analysis of the EO properties shows exceptional poling efficiency of these binary systems at high chromophore loading levels, in contrast to experimental results obtained from single-chromophore polymers.