From the Preface by A. von Hippel: Since Debye postulated the existence of permanent dipole moments, this molecular constant has become of decisive importance for the interpretation of the dielectric properties of gases, liquids, and solids. More than twenty-five hundred compounds have been measured to date, many under a variety of conditions and by a number of different methods. These substances were selected according to the diverse interests of the investigators, and the results are scattered in the physical and chemical literature of many countries.We felt the need, from the standpoint of coordinated research on dielectrics, for a well-organized compilation of these dipole moments, and L. G. Wesson of this Laboratory has undertaken the arduous and exacting task. It is hoped that the Tables of Electric Dipole Moments will prove of value to all research workers in this field, as well as future authors, in making these Tables more reliable, complete, and up-to-date.