On July 10, 1980, Kenneth S. Cole became 80 years old. In order to celebrate this landmark, a symposium in the form of a series of Monday evening lectures was held in his honor at the Marine Biological Labora tory throughout the summer of 1980. The selection of speakers was made from among those investigators who had been either his students or co-workers. One intent of the symposium was to examine the current status of knowledge of those areas of interest in excitable membrane structure and function that owe their initiation or encouragement to Kacy Cole. The papers assembled in this volume represent a large majority of the presentations given during the 1980 Cole Symposium. It seems clear on examination of these papers that Kacy’s interests in membrane impedance, ion channel conductances, channel fluctuation phenomena, excitation, and the development of membrane biophysical methodology are all being actively pursued. It is also clear that many of his suggestions have borne fruit. Of these, his invention of the voltage v vi Preface clamp method has been most productive. It is hoped that these papers will provide new directions for investigations into the nature of excitable membrane phenomena. The organizers of the symposium and the editors of this volume wish to express their thanks to the Marine Biological Laboratory for making available the facilities for the symposium. They also wish to thank Dr.