Specific heat and thermal expansion are closely related. Following a discussion on thermal expansion theory, methods of measurement techniques are presented along with their advantages and disadvantages. The results of the measurements are then summarized for three classes of materials: metallics, nonmetallics, and composites. Because predicting thermal expansion values for unmeasured or novel materials is useful, the chapter also describes the means of making educated guesses for low-temperature values. A short discussion on how thermal expansion data can be used is followed by a section describing where such data can be found.