Edible films and barriers derived from polysaccharides, proteins and lipids provide several functions which prevent mass transfer, for example, water vapor, gas, and volatile compounds, between foods and environment. The preparation of materials can be either by solution casting commonly used in the laboratory or a more commercially extrusion process. Plasticizers are used to increase deformability reducing the glass transition temperature (Tg) of the materials which can be determined using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). This chapter also demonstrates the effects of plasticizers, other components, and treatments on the Tg values of various edible films. Moreover, the non-equilibrium state of the edible film matrices causes several time-dependent changes during storage or “aging,” for example, plasticizer loss, lipid destabilization, and crystallization which subsequently impacts functional and mechanical properties of the films.