This paper describes a novel, versatile system for measuring the stress sensitivity of magnetostriction of Epstein strips of grain-oriented electrical steel, an analysis of results of measurements on several grades of commercial material, and an attempt to relate their stress sensitivity characteristics to material properties. The maximum value of peak magnetostriction under applied stress is proportional to the strip gauge for both conventional and high permeability grades of material. A model explains the contributions of retained stress and stress due to the forsterite coatings on grain-oriented silicon steel. This model can be used to correlate the thickness of the fosterite coating to its calculated coating stress. It is also possible to separate the effect of the phosphate and forsterite coatings. Both types of coating set up a longitudinal stress in the steel in proportion to their thickness.