We have successfully made thin film transistors on transparent, flexible polymer substrates. These transistors have electrical properties suitable for driving the pixels in active matrix liquid crystal displays and also for building integrated row driver circuits. The devices are fabricated on polyethylene naphthalate using a low temperature CdSe process at a maximum temperature of 150 degrees C, by evaporation and radio frequency sputtering onto unheated substrates. with pattern definition using standard photolithography and etching. Electrical properties achieved include carrier field effect mobilities of >30 cm(2)/Vs, threshold voltages of similar to 2 V) switching ratio >10(6), an off-state leakage current of <10(-12) A and an on-state drive current of >1 mu A with a gate voltage swing of <10 V, and a sub-threshold slope of 0.25 V/decade for devices of unity aspect ratio. The electrical properties were found to scale with device channel length and width.