This book is a compilation of formal presentations made during a three-day invitational conference at Battelle Research Center in Seattle, Washington. The purpose of organizing and publishing the proceedings of the conference is to provide a comprehensive survey of present knowledge on the determinants of membrane structure, the molec­ ular specificity of membrane function, and the dynamic properties of membranes. Each presentation was followed by discussions which, because of their informal and spontaneous character, have not been included in this publication. Molecular studies of biological membrane phenomena have progressed over the past decade to the point where it is now realistic to expect future resolution of the physico-chemical processes or forces governing the organization, function, and dynamic properties of membranes. Drs. Radda, Kaback, and Schwyzer, each presenting a different approach to the biochemical and biophysical study of membranes, devoted four to six weeks as Battelle Visiting Fellows to developing the format and the roster of participants of the conference. The scientific "cluster" concept for planning the conference is reflected in the breadth of topics presented in this publication.