Concepts and applications of laboratory or sensitivity training are discussed, with a brief history of the development, goals, and underlying system of values of the National Training Laboratories. Processes which occur during a sensitivity training experience are traced, with particular emphasis on dynamics of T group development and the assumption of appropriate trainer roles or functions under various conditions. Possible outcomes are suggested for individual learners as well as in family life, industry and government, community affairs, and other settings. Reservations and differences of opinion expressed by "insiders" (professional practitioners or those in related vocations) are examined, followed by criticisms by skeptical or hostile "outsiders" who view sensitivity training as trivial, immoral, subversive, or emotionally damaging. Typical problems in transfer of training to personal and organizational life are also noted. While warning that sensitivity training is not to be undertaken lightly or regarded as a panacea, the author offers indications that people who participate under competent, reputable trainers can encounter more productive ways of behaving with and relating to others. The document includes 37 references. (LY)