As a sequel to the Workshops held at Culham Laboratory in June 1978 and at Lawrence Berkeley National Laboratory (LBNL) in November 1979, the Third Workshop on the Development of Neutral Beam Injectors for Plasma Heating was held in Gatlinburg, Tennessee, October 19–23, 1981. Approximately 80 persons participated in the meeting. The Workshop was organized by the Oak Ridge National Laboratory (ORNL) and was jointly sponsored by the United States Department of Energy and the International Atomic Energy Agency. The programme was devoted primarily to the development of positive-ion-based neutral injectors, although one session was allotted to discussions on the production of negative ion beams. The Workshop was conducted in an informal way to permit maximum interaction among the participants in the form of discussions rather than formal presentations. Nevertheless, the participants were asked to submit camera-ready manuscripts of their contributions for publication in the form of Conference Proceedings.