Sheet materials with low thermal expansion are employed in the construction of certain precision components and must display excellent dimensional stability. Measurement of small dimensional changes in sheet materials over long periods of time (of the order of two parts per million per year) poses severe experimental problems when conventional measuring techniques such as interferometry are used. To avoid these difficulties, experiments were conducted to explore the usefulness of bonded electrical resistance strain gauges for measuring the dimensional stability of sheet specimens. Based on the results obtained, it is concluded that the strain gauge method is capable of detecting gradual length changes as small as about 1 or 2 parts per million over time periods approaching one year.