The International Workshop - Conference on Atherosclerosis was held at the University of Western Ontario, London, Ontario, Canada, September 1 - 3, 1975. This book does not represent in a strict sense the entire proceedings of the above Workshop - Conference, but does reflect largely the format and the essential content of the scientific sessions. Thus, each of the three Sections of the book is comprised of the summarized presentations either at the Plenary Sessions (Section I), Proffered Papers (Section II) or Workshops (Section III). Section I comprises all the presentations of the Plenary Session on September 1 and the first three presentations at the Plenary Session on the last day of the Conference (September 3). The remaining two addresses of the latter Session (Resume of Workshop - Conference and Closing Remarks) follow the Section III at the end of the book. Sections II and III are subdivided into Chapters which correspond to the individual Sessions of Proffered Papers and Workshops, respectively. To facilitate the orientation, particularly for those who attended the Workshop - Conference, a Summary Table of all Sessions of Proffered Papers designated as Chapters in this book, precedes Section II, and a similar Summary Table of Workshops, also designated as Chapters, precedes Section III. The Tables include, in addition, the names of both Chairmen of each Session. The Chairmen whose names do not appear on either Summary Table are those who chaired the two Plenary Sessions, i. e.