This book considers the possibility that life may have originated or existed on a body from which a sample might be taken and the possibility that life still exists on the body either in active form or in a form that could be reactivated. It also addresses the potential hazard to terrestrial ecosystems from extraterrestrial life if it exists in a returned sample. Released at the time of the Internationl Committee on Space Research General Assembly, the book has already established the basis for plans for small body sample retruns in the international space research community.