What are the implications for Humankind of alien civilizations that may be 'out there?' In thinking about contact with extraterrestrials, we have to grapple with a host of philosophical, religious, and societal questions. The biggest is whether the outcome of contact will be beneficial or harmful. Will contact uplift us, bringing a golden age of wisdom and prosperity? Or will it demoralize, even destroy us? This thought-provoking book presents a rainbow of opinions expressed by scientists, sociologists, historians, legal and political thinkers, and many others. The author takes into account not only scientific speculation, but also fiction and popular opinion. He challenges the most frequent assumptions that unerlie our thinking. He looks at both sides of the 'where are they' debate, questioning the alleged paradox and proposing new ways of thinking about the issue. The serious practical questions raised by extraterrestrial intelligence are becoming harder to avoid as our search technologies and methods improve, as we identify ever-greater numbers of planets orbiting other stars, and as the wave front of our radio, television, and radar signals reaches out into the Galaxy. How should we deal with contact if it happens? What do we want to say to an extraterrestrial civilization? Will we speak as one, or as many? What should we do if we find alien technology in our solar system? Should we simply be watchers and listeners, or should we actively seek contact by sending out messages proclaiming our presence? Our answers reveal our hopes and our fears.