A temperature difference across a sample of vacuum glazing causes differential expansion of one glass sheet relative to the other. In vacuum glazing with a fused edge seal, this results in tensile and compressive stresses in the glass sheets, and bending of the structure. The physical origins of these stresses and deflections are discussed, and a finite element model is used to determine their magnitude. The model has been validated by comparison with experimental data for a well-characterised sample of vacuum glazing under accurately defined external conditions. Modelling data are presented for two glazing designs which have properties that are characteristic of the extremes of performance of this type of glazing. It is shown that mechanical edge constraints can profoundly alter the spatial distribution of stresses in the glazing.