The results of a study on the effects of a plasticizer, tricresyl phosphate, on the mechanical and thermal properties of unoriented films of poly(vinylidene fluoride-trifluoroethylene) (VF2/VF3) copolymer (73/27 mol%) are presented. Films were prepared by both quenching and slow-cooling from the melt with plasticizer concentrations of 0, 5, and 10% by weight. For the slow-cooled films, a reduction in crystallinity by 25% was observed for the heavily plasticized films, together with a reduced dynamic mechanical modulus (approximate to 58%) and an increased dielectric constant (approximate to 200%). For the quenched films, a small increase in crystallinity was observed together with a reduced modulus and an increased dielectric constant. Measurements of the temperature dependence of the modulus and dielectric constant at 10 Hz. were also carried out from -100 degrees C to 100 degrees C. This data showed that for slow-cooled films the glass transition temperature decreased from -28 degrees C to -52 degrees C at the highest doping level. DSC thermal analysis shows a decrease in the Curie transition (approximate to 4 degrees C) and melting temperatures (approximate to 9 degrees C) for the quenched films, while the slow-cooled films only showed a decrease in melting temperature (approximate to 10 degrees C), while the Curie transition temperature was unaffected. In addition, evidence of a two-phase system or a nonferroelectric crystal phase is noted by the presence of two Curie transition temperature peaks.