This paper selectively examines past experience in science and technology cooperation with a view to identifying the key characteristics accounting for successful and less successful ventures that might be applicable to fusion research, development, and demonstration activities. Included in the analysis are the European Organization for Nuclear Research; Euratom; the Joint European Torus; the Nuclear Energy Agency's Eurochemic, Dragon, and Halden projects; European breeder cooperation; Urenco; and INTELSAT. The analysis takes as a point of departure the proposition that past experiences carry limited and selective lessons for shaping future enterprises, that there is no single generic model of cooperation that can simply be applied to new ventures, and that success is likely to be more probable where the organization and ground rules have been tailored to accommodate the objectives to be achieved, the character of the participants, and the salient environing political factors.