Biotechnologies already on the horizon will enable us to be smarter, have better memories, be stronger and quicker, have more stamina, live longer, be more resistant to diseases, and enjoy richer emotional lives. To some of us, these prospects are heartening; to others, they are dreadful. InBeyond Humanitya leading philosopher offers a powerful and controversial exploration of urgent ethical issues concerning human enhancement. These raise enduring questions about what it is to be human, about individuality, about our relationship to nature, and about what sort of society we should strive to have. Allen Buchanan urges that the debate about enhancement needs to be informed by a proper understanding of evolutionary biology, which has discredited the simplistic conceptions of human nature used by many opponents of enhancement. He argues that there are powerful reasons for us to embark on the enhancement enterprise, and no objections to enhancement that are sufficient to outweigh them.