This study investigates the influence of semipermeable functional films on the sur face vapor pressure and temperature of fabric-film-fabric assemblies. The film added between two fabric layers affects vapor pressure and temperature changes on both surfaces of the assembly under simulated body-clothing conditions. The physical char acteristics of films greatly influence the level of transient, comfort-related variables such as changes of inner surface vapor pressure and temperature. Mixed cotton and polyester layers of a film reveal that the film can negatively affect moisture sorption of the assembly, not only by blocking the air spaces for moisture diffusion, but more importantly, by ineffective heat dissipation from the cotton inner fabric for continued moisture sorption. Using film and fabric assemblies, this study reinforces the interde pendence of moisture sorption and temperature barrier effects during dynamic moisture transfer through clothing assemblies. Fiber hygroscopicity of the layered fabrics and physical properties of breathable waterproof film are more important than the hygro scopicity of film in determining comfort performance of multilayer functional clothing in transient conditions.