The second harmonic generation (SHG) coefficientsdijof several corona‐poled guest‐host and side‐chain polymers have been measured and studied over time using a new Maker Fringe analysis. The electro‐optic coefficientr33and scattering losses have also been measured in thin‐film waveguides, on silicon and glass substrates, made from some of the polymers. Kleinman symmetry (d15=d31) was not valid for near‐resonant SHG in these materials andd15/d31was determined. Stable values ofd33, for a fundamental of 1.064 &mgr;m, were as high as 40 pm/V for one of the side‐chain polymers. Optical waveguide losses determined from scattering measurements were as low as 0.4 dB/cm at 1.06 &mgr;m.