On March 26-27, 1980, a symposium organized by one of us (P. P. ) was held at the l79th American Chemical Society National ~1eeting in Houston, Texas, under the sponsorship of the Theoretical Chemistry Subdivision of the Division of Physical Chemistry. The symposium was entitled "The Role of the Electrostatic Potential in Chemistry," and it served as a stimulus for this book. The original scope and coverage have been broadened, however; included here, in addition to contributions from the eleven invited symposium speakers and two of the poster-session participants, are four papers that were specially invited for this book. Furthermore, several authors have taken this opportunity to present at least partial reviews of the areas being discussed. Most of the manuscripts were completed in the late spring and early summer of 1980. We hope that this book will achieve two goals: First, we are trying to provide an overall picture, including recent advances, of current chemical research, both fundamental and applied, involving the electrostatic potential. Second, we want to convey an appreci­ ation of both the powers and also the limitations of the electro­ static potential approach. In order to achieve these goals, we have selected contributors whose research areas provide a very broad coverage of the field. Throughout the book, we have used a. u.