In the summer of 1969, the first Workshop on Control of Renin Secretion was held at Stanford University. At its completion, it was suggested by many of those who attended that a second Workshop be planned in about two years time. Thus the second Workshop on Control of Renin Secretion took place and from this event the chapters in this book had their origin. The setting of this Work­ shop was the beautiful J & R Double Arch Ranch in Santa Ynez, California which houses the Kroc Foundation. The Foundation, through the kindness of its President, Dr. Robert L. Kroc, provided us with luxurious accommodations, excellent meeting facilities and an atmosphere extremely conducive to the exchange of scientific knowledge, both formally and informally. In addition, the Founda­ tion assisted financially in the travel expenses of three of our foreign guests and in the preparation of the manuscripts for this book. I know I speak for all of us who attended the Workshop in expressing our sincere gratitude to the Foundation and to Dr. and Mrs. Kroc and their staff. In addition, I personally, as organizer of the meeting and editor, wish to acknowledge the help of many others who made my job much easier. Drs. Davis, Ganong, Luetscher and Tobian kindly took on the jobs of chairing the four sessions and directing the lively discussions which followed each presentation.