Judging by the increasing number of articles appearing in the literature, it appears safe to say that Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA) are gaining acceptance and finding ever increasing use in the field of chemistry. The fact that this acceptance and increased interest is comparatively recent is really quite remarkable when one considers the comparative ease with which the techniques can be performed, and the many areas of applicability for them. This recent interest in two old techniques is probably related to two facts. First, the need for time-consuming construction of elaborate, precise equipment apparently previously presented too great an obstacle to all except the serious student or practitioner. Therefore, it was not possible for most workers to use routinely, or to investigate the utility of these thermal methods. This problem has been solved by the development and commercial availability of reliable, high-sensitivity equipment. Second, the polymer chemist has discovered the utility of these techniques and is beginning to exploit them. Because of the great size and scope of the field of polymer chemistry, this area may soon become the largest contributor to the thermal analysis literature. As one reviews the available literature on the application of DTA and TGA to polymers it becomes apparent that most of the articles, including reviews, are concerned with plastics—and that investigations of elastomers are actually few in number and relatively recent. One possible reason for this is that many of the plastics applications for DTA are concerned with the measurement of various aspects of crystallinity in polymers of high degree of crystallinity, especially polyolefins.