We examine the linear electro‐optic response of a polymer thin film to an applied step function poling electric field. Time‐resolved measurement of the electro‐optic response is compared to theory. The electro‐optic response measurement uses a heterodyne interferometric technique not previously reported. Response rise and fall times of the order of milliseconds are resolvable and the temperature dependence of those times reported. Good qualitative agreement between theory and data is presented.