The first international conference on the problem of extraterrestrial civilizations, and contact with them, was held in September 1971 in Soviet Armenia. The conference was a gathering of specialists working in a wide variety of fields—astronomy, physics, radiophysics, computer science and technology, chemistry, biology, linguistics, archaeology, anthropology, sociology, and history—and included many scientists whose reputations are worldwide. For example, Freeman Dyson, Philip Morrison, and Charles Townes were among the American participants; their Russian counterparts were of comparable distinction. The conference was jointly organized by the U.S. National Academy of Sciences (with assistance from the U.S. National Science Foundation) and the U.S.S.R. Academy of Sciences. Scientists from several other countries also participated. Many aspects of the problem of extraterrestrial civilizations were discussed in detail, and these discussions are fully presented in this book. Particular attention is devoted to the following questions: the plurality of planetary systems in the universe, the origin of life on Earth, the possibility of life arising on cosmic bodies, the origin and evolution of intelligence, the origin and development of technological civilizations, problems in searching for intelligent signals or for evidence of astroengineering activities, and the problems and possible consequences of establishing contact with extraterrestrial civilizations.