The scope of each chapter and the focus of the papers in this volume were developed in two workshops held in Orlando, Fla., during January1982. Each of the papers was peer reviewed by the authors contributing to the chapter. The reviews were for technical accuracy and clarity; no premium was placed on consensus views . Individual and bold positions were encouraged. An iterative review and revision process was carried out to achieve balanced coverage of the prospects and barriers to advanced space propulsion. Where appropriate, the authors included statements on research needs and approaches. Chapter I treats several aspects of beamed energy propulsion, i.e., power sources and transmission, radiation absorption in flowing media, and thruster configurations. Chapter II, the first chapter on electric propulsion, emphasizes concepts that lend themselves to sustained operation at megawatt power levels, possibly using clusters of thrusters. Chapter III, the second chapter on electric propulsion, deals with the concepts that by their nature operate in the pulsed mode. Nuclear propulsion, as discussed in Chapter IV, includes either direct heating of the working fluid (i.e., hydrogen) by fission reactors or nuclear electric power systems to drive electric thrusters. The final paper in the volume is in the chapter on advanced chemical propulsion.