A method for determining the stresses in a film applied to a substrate from measured substrate shape. The substrate is first analyzed using finite element techniques to obtain nodal forces at the surface of the substrate to which the film is applied, based on measured distortion data of the substrate surface. The film is then analyzed to calculate the film stresses from the applied nodal forces using finite element techniques. The invention may be applied to determine stresses in thin films applied to a variety of substrates, including those used for micro-electronic (e.g., integrated circuit) and micro-mechanical devices and/or for the lithography masks or other optical/projection systems used to fabricate such devices.