In recent years, great effort has been paid to "Integrated Ferroelectrics", i.e. the integration of ferroelectric thin films with Si or GaAs chips for developing new devices or systems. Another interesting and potential important area for the investigation of ferroelectric thin films may be the integration of ferroelectric thin films with related functional films, such as piezoelectric and nonlinear optic thin films, for developing multifunctional devices or smart film devices by using the nonlinear or cross - coupling effects based on the interaction of elastic, thermal, electric, magnetic and optical fields in ferroelectric thin films. In this paper, we present some fundamental aspects of ferroelectric integrated thin films from both phenomenological and fabrication points of view, and give some examples of potential devices which can be made from ferroelectric integrated thin films.