This book contains the invited talks from the 1995 Boulder conference on the Search for Extra-Solar Planets. It describes the scientific basis, technological options, and programmatic implications of large-scale efforts to find and study Earth-like planets outside the Solar System, and is targeted at astronomers, planetary scientists, engineers, and graduate students. These are among the first papers in this rapidly expanding field, driven by the first discoveries of planetary companions to nearby stars and providing the current status of the search for extra-solar planets. What sort of objects are we looking for in planetary atmospheres and planetary-system architectures? What techniques are currently feasible, both from the ground and in space? How can interferometers be optimized to discern faint planets in the glare of their parent stars? The detection and study of Earth-like planets outside our Solar System will be one of the great scientific, technological, and philosophical events of our time, affecting our understanding of the Universe and the place of life within it.