What moral reasons, if any, do we have to ensure the long-term survival of humanity? This article contrastively explores two answers to this question: according to the first, we should ensure the survival of humanity because we have reason to maximize the number of happy lives that are ever lived, all else equal. According to the second, seeking to sustain humanity into the future is the appropriate response to the final value of humanity itself. Along the way, the article discusses (...) various issues in population axiology, particularly the so-called Intuition of Neutrality and John Broome’s ‘greediness objection’ to this intuition. (shrink)